SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    82038, 148882, 148883, 148884, 148885, 
    148886, 148887, 148888, 148889, 148890, 
    148891, 148892, 148893, 148894, 148895, 
    148896, 148897, 148898, 148899, 148900, 
    148901, 148902, 148903, 148904, 148905, 
    148906, 148907, 148908, 148909, 148910, 
    148911, 148912, 148913, 148914, 148915, 
    148916, 148917, 148918, 148919, 148920, 
    148921, 148922, 148923, 148924, 148925, 
    148926, 148927, 148928, 148929, 148930, 
    148931
  ) 
  AND feature_id IN (548, 549) 
  AND lang_code = 'en'

Query time 0.00378

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "42.07"
    },
    "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": "lang_code",
      "used_key_parts": [
        "lang_code",
        "feature_id",
        "product_id"
      ],
      "key_length": "12",
      "rows_examined_per_scan": 102,
      "rows_produced_per_join": 102,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "21.67",
        "eval_cost": "20.40",
        "prefix_cost": "42.07",
        "data_read_per_join": "78K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_features_values`.`product_id` in (82038,148882,148883,148884,148885,148886,148887,148888,148889,148890,148891,148892,148893,148894,148895,148896,148897,148898,148899,148900,148901,148902,148903,148904,148905,148906,148907,148908,148909,148910,148911,148912,148913,148914,148915,148916,148917,148918,148919,148920,148921,148922,148923,148924,148925,148926,148927,148928,148929,148930,148931)) and (`webmarco`.`cscart_product_features_values`.`feature_id` in (548,549)) and (`webmarco`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}