SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    7272, 7273, 7274, 7275, 7276, 7277, 7347, 
    7348, 7349, 7350, 1329, 1325, 1327, 
    1328, 5075, 5071, 5073, 5074, 1333, 
    1331, 1332, 5077, 5078, 6714, 3687
  ) 
  AND feature_id IN (
    625, 624, 628, 595, 641, 637, 636, 627, 
    623, 622, 626, 553
  ) 
  AND lang_code = 'en'

Query time 0.00510

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.77"
    },
    "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": 300,
      "rows_produced_per_join": 300,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "37.77",
        "eval_cost": "30.00",
        "prefix_cost": "67.77",
        "data_read_per_join": "232K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`gaseus`.`cscart_product_features_values`.`product_id` in (7272,7273,7274,7275,7276,7277,7347,7348,7349,7350,1329,1325,1327,1328,5075,5071,5073,5074,1333,1331,1332,5077,5078,6714,3687)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (625,624,628,595,641,637,636,627,623,622,626,553)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}