SELECT 
  cscart_product_feature_variant_descriptions.variant, 
  cscart_product_feature_variants.variant_id, 
  cscart_product_feature_variants.feature_id, 
  cscart_product_features_values.variant_id as selected, 
  cscart_product_features.feature_type, 
  cscart_seo_names.name as seo_name, 
  cscart_seo_names.path as seo_path 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variant_descriptions.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'en' 
  INNER JOIN cscart_product_features_values ON cscart_product_features_values.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_features_values.lang_code = 'en' 
  AND cscart_product_features_values.product_id = 264973 
  AND cscart_product_features_values.feature_id = cscart_product_feature_variants.feature_id 
  LEFT JOIN cscart_product_features ON cscart_product_features.feature_id = cscart_product_feature_variants.feature_id 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = cscart_product_feature_variants.variant_id 
  AND cscart_seo_names.type = 'e' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'en' 
WHERE 
  1 
  AND cscart_product_feature_variants.feature_id IN (
    992, 989, 998, 995, 997, 991, 990, 993, 
    996, 994, 882, 649, 735
  ) 
GROUP BY 
  cscart_product_feature_variants.variant_id 
ORDER BY 
  cscart_product_feature_variants.position, 
  cscart_product_feature_variant_descriptions.variant

Query time 0.00320

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "31.31"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": false,
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_features_values",
              "access_type": "range",
              "possible_keys": [
                "PRIMARY",
                "fl",
                "variant_id",
                "lang_code",
                "product_id",
                "fpl",
                "idx_product_feature_variant_id"
              ],
              "key": "lang_code",
              "used_key_parts": [
                "lang_code",
                "feature_id",
                "product_id"
              ],
              "key_length": "12",
              "rows_examined_per_scan": 17,
              "rows_produced_per_join": 17,
              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "4.45",
                "eval_cost": "3.40",
                "prefix_cost": "7.85",
                "data_read_per_join": "13K"
              },
              "used_columns": [
                "feature_id",
                "product_id",
                "variant_id",
                "lang_code"
              ],
              "attached_condition": "((`webmarco`.`cscart_product_features_values`.`product_id` = 264973) and (`webmarco`.`cscart_product_features_values`.`feature_id` in (992,989,998,995,997,991,990,993,996,994,882,649,735)) and (`webmarco`.`cscart_product_features_values`.`lang_code` = 'en'))"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variants",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "feature_id",
                "position"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id"
              ],
              "key_length": "3",
              "ref": [
                "webmarco.cscart_product_features_values.variant_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 0,
              "filtered": "5.00",
              "cost_info": {
                "read_cost": "17.00",
                "eval_cost": "0.17",
                "prefix_cost": "28.25",
                "data_read_per_join": "992"
              },
              "used_columns": [
                "variant_id",
                "feature_id",
                "position"
              ],
              "attached_condition": "(`webmarco`.`cscart_product_feature_variants`.`feature_id` = `webmarco`.`cscart_product_features_values`.`feature_id`)"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_features",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "feature_id"
              ],
              "key_length": "3",
              "ref": [
                "webmarco.cscart_product_features_values.feature_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 0,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "0.85",
                "eval_cost": "0.17",
                "prefix_cost": "29.27",
                "data_read_per_join": "374"
              },
              "used_columns": [
                "feature_id",
                "feature_type"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variant_descriptions",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id",
                "lang_code"
              ],
              "key_length": "9",
              "ref": [
                "webmarco.cscart_product_features_values.variant_id",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 0,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "0.85",
                "eval_cost": "0.17",
                "prefix_cost": "30.29",
                "data_read_per_join": "3K"
              },
              "used_columns": [
                "variant_id",
                "variant",
                "lang_code"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_seo_names",
              "access_type": "ref",
              "possible_keys": [
                "PRIMARY",
                "dispatch"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "object_id",
                "type",
                "dispatch",
                "lang_code"
              ],
              "key_length": "206",
              "ref": [
                "webmarco.cscart_product_features_values.variant_id",
                "const",
                "const",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 0,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "0.85",
                "eval_cost": "0.17",
                "prefix_cost": "31.31",
                "data_read_per_join": "1K"
              },
              "used_columns": [
                "name",
                "object_id",
                "company_id",
                "type",
                "dispatch",
                "path",
                "lang_code"
              ]
            }
          }
        ]
      }
    }
  }
}

Result

variant variant_id feature_id selected feature_type seo_name seo_path
- Senza marca/Generico - 64439 989 64439 S
36 64441 991 64441 S
36 7836 735 7836 M
37 7837 735 7837 M
38 7838 735 7838 M
39 7839 735 7839 M
40 7840 735 7840 M
Beige 64442 992 64442 S
Beige 60412 882 60412 S
Comfortable Sneaker 64447 997 64447 S
Donna 64440 990 64440 S
EU 36 62608 649 62608 S
Microfibra 64445 995 64445 S
Microfibra 64449 998 64449 S
Scarpa 64444 994 64444 S
Sneaker 64443 993 64443 S
Sneaker 64446 996 64446 S