SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    13031, 13032, 13033, 13034, 13035, 13036, 
    13037, 13038, 13039, 13028, 13029, 
    13030
  ) 
  AND feature_id IN (
    646, 647, 595, 628, 627, 624, 625, 553, 
    626, 622, 623, 636, 637
  ) 
  AND lang_code = 'en'

Query time 0.00559

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "9.73"
    },
    "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": "PRIMARY",
      "used_key_parts": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "key_length": "15",
      "rows_examined_per_scan": 27,
      "rows_produced_per_join": 27,
      "filtered": "100.00",
      "using_index_for_skip_scan": true,
      "cost_info": {
        "read_cost": "7.03",
        "eval_cost": "2.70",
        "prefix_cost": "9.73",
        "data_read_per_join": "20K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`test2_gaseus`.`cscart_product_features_values`.`product_id` in (13031,13032,13033,13034,13035,13036,13037,13038,13039,13028,13029,13030)) and (`test2_gaseus`.`cscart_product_features_values`.`feature_id` in (646,647,595,628,627,624,625,553,626,622,623,636,637)) and (`test2_gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id feature_id variant_id
13028 553 1973
13029 553 1973
13030 553 1973
13031 553 1973
13032 553 1973
13033 553 1973
13034 553 1973
13035 553 1973
13036 553 1973
13037 553 1973
13038 553 1973
13039 553 1973
13028 595 1904
13029 595 1904
13030 595 1905
13031 595 1905
13032 595 2451
13033 595 2451
13034 595 1787
13035 595 1787
13036 595 1900
13037 595 1900
13038 595 1899
13039 595 1899
13028 622 2497
13029 622 2497
13030 622 2497
13031 622 2497
13032 622 2497
13033 622 2497
13034 622 2497
13035 622 2497
13036 622 2497
13037 622 2497
13038 622 2497
13039 622 2497
13028 623 2501
13029 623 2501
13030 623 2501
13031 623 2501
13032 623 2501
13033 623 2501
13034 623 2501
13035 623 2501
13036 623 2501
13037 623 2501
13038 623 2501
13039 623 2501
13028 624 1803
13029 624 1803
13030 624 1803
13031 624 1803
13032 624 1803
13033 624 1803
13034 624 1803
13035 624 1803
13036 624 1803
13037 624 1803
13038 624 1803
13039 624 1803
13028 625 2515
13029 625 2515
13030 625 2515
13031 625 2515
13032 625 2515
13033 625 2515
13034 625 2515
13035 625 2515
13036 625 2515
13037 625 2515
13038 625 2515
13039 625 2515
13028 626 2032
13029 626 2032
13030 626 2032
13031 626 2032
13032 626 2032
13033 626 2032
13034 626 2032
13035 626 2032
13036 626 2032
13037 626 2032
13038 626 2032
13039 626 2032
13028 627 1659
13029 627 1659
13030 627 1659
13031 627 1659
13032 627 1659
13033 627 1659
13034 627 1659
13035 627 1659
13036 627 1659
13037 627 1659
13038 627 1659
13039 627 1659
13028 628 1660
13029 628 1660
13030 628 1660
13031 628 1660
13032 628 1660
13033 628 1660
13034 628 1660
13035 628 1660
13036 628 1660
13037 628 1660
13038 628 1660
13039 628 1660
13028 636 2348
13029 636 2348
13030 636 2348
13031 636 2348
13032 636 2348
13033 636 2348
13034 636 2348
13035 636 2348
13036 636 2348
13037 636 2348
13038 636 2348
13039 636 2348
13028 637 2345
13029 637 2345
13030 637 2345
13031 637 2345
13032 637 2345
13033 637 2345
13034 637 2345
13035 637 2345
13036 637 2345
13037 637 2345
13038 637 2345
13039 637 2345
13028 646 2369
13029 646 2370
13030 646 2369
13031 646 2370
13032 646 2369
13033 646 2370
13034 646 2369
13035 646 2370
13036 646 2369
13037 646 2370
13038 646 2369
13039 646 2370
13028 647 2373
13029 647 2374
13030 647 2373
13031 647 2374
13032 647 2373
13033 647 2374
13034 647 2373
13035 647 2374
13036 647 2373
13037 647 2374
13038 647 2373
13039 647 2374