SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    11005, 11006, 11007, 11008, 11009, 11010, 
    11011, 11012, 11013, 11014, 11015, 
    11016, 11017, 11018, 11019, 11020, 
    11021, 11022, 11023, 11024, 11025, 
    11026
  ) 
  AND feature_id IN (553, 624, 623) 
  AND lang_code = 'en'

Query time 0.00616

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "15.36"
    },
    "table": {
      "table_name": "cscart_product_features_values",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "fl",
        "lang_code",
        "product_id",
        "fpl",
        "idx_product_feature_variant_id"
      ],
      "key": "idx_product_feature_variant_id",
      "used_key_parts": [
        "product_id",
        "feature_id",
        "lang_code"
      ],
      "key_length": "12",
      "rows_examined_per_scan": 66,
      "rows_produced_per_join": 66,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "8.76",
        "eval_cost": "6.60",
        "prefix_cost": "15.36",
        "data_read_per_join": "51K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`gaseus`.`cscart_product_features_values`.`product_id` in (11005,11006,11007,11008,11009,11010,11011,11012,11013,11014,11015,11016,11017,11018,11019,11020,11021,11022,11023,11024,11025,11026)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (553,624,623)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}