SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    262226, 262225, 262224, 262227, 269827, 
    262223, 309437, 269816, 270028, 269815, 
    269817, 269818, 269814, 269830, 435278, 
    435279, 269820, 269833, 269819, 269821
  )

Query time 0.00095

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "86.04"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 20,
          "rows_produced_per_join": 20,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "24.03",
            "eval_cost": "4.00",
            "prefix_cost": "28.03",
            "data_read_per_join": "320"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ],
          "attached_condition": "(`webmarco`.`p`.`product_id` in (262226,262225,262224,262227,269827,262223,309437,269816,270028,269815,269817,269818,269814,269830,435278,435279,269820,269833,269819,269821))"
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "webmarco.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 20,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "20.00",
            "eval_cost": "4.00",
            "prefix_cost": "52.03",
            "data_read_per_join": "7K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": [
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "webmarco.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 28,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "28.34",
            "eval_cost": "5.67",
            "prefix_cost": "86.04",
            "data_read_per_join": "2K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}