SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    7159, 7160, 7161, 7162, 7163, 7164, 7165, 
    67587, 7168, 7166, 7167, 67588, 7169, 
    7170, 7171, 60615, 64546, 67701, 38285, 
    64691, 64236, 64062, 65302, 64475
  )

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "62.44"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "rows_examined_per_scan": 24,
          "rows_produced_per_join": 24,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "28.84",
            "eval_cost": "4.80",
            "prefix_cost": "33.64",
            "data_read_per_join": "108K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ],
          "attached_condition": "((`webmarco`.`pfvd`.`variant_id` in (7159,7160,7161,7162,7163,7164,7165,67587,7168,7166,7167,67588,7169,7170,7171,60615,64546,67701,38285,64691,64236,64062,65302,64475)) and (`webmarco`.`pfvd`.`lang_code` = 'en'))"
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "webmarco.pfvd.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 24,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "24.00",
            "eval_cost": "4.80",
            "prefix_cost": "62.44",
            "data_read_per_join": "27K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      }
    ]
  }
}