SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    12683, 12661, 12662, 12663, 12664, 12665, 
    12666, 12667, 12668, 12669, 12670, 
    12671, 12672, 12673, 12674, 12675, 
    12676, 12677, 12678, 12679, 12680, 
    12681, 12682, 12660, 12659, 12658, 
    12657, 12656, 12655, 12654
  ) 
  AND feature_id IN (553, 625, 624, 627, 628) 
  AND lang_code = 'en'

Query time 0.00628

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "11.09"
    },
    "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": 32,
      "rows_produced_per_join": 32,
      "filtered": "100.00",
      "using_index_for_skip_scan": true,
      "cost_info": {
        "read_cost": "7.89",
        "eval_cost": "3.20",
        "prefix_cost": "11.09",
        "data_read_per_join": "24K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`test2_gaseus`.`cscart_product_features_values`.`product_id` in (12683,12661,12662,12663,12664,12665,12666,12667,12668,12669,12670,12671,12672,12673,12674,12675,12676,12677,12678,12679,12680,12681,12682,12660,12659,12658,12657,12656,12655,12654)) and (`test2_gaseus`.`cscart_product_features_values`.`feature_id` in (553,625,624,627,628)) and (`test2_gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}