SELECT 
  category_id, 
  category 
FROM 
  cscart_category_descriptions 
WHERE 
  category_id IN (
    337, 338, 339, 340, 341, 342, 343, 344, 
    345, 347, 349, 350, 351, 352, 353, 354, 
    355, 356, 357, 358, 359, 360, 361, 362, 
    363, 368, 369, 370, 371, 372, 373, 374, 
    375, 376, 377, 378, 388, 390, 391, 392, 
    393, 394, 395, 396
  ) 
  AND lang_code = 'de'

Query time 0.00077

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "105.61"
    },
    "table": {
      "table_name": "cscart_category_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "category_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 44,
      "rows_produced_per_join": 44,
      "filtered": "100.00",
      "index_condition": "((`eshopuga_upgr_4122`.`cscart_category_descriptions`.`category_id` in (337,338,339,340,341,342,343,344,345,347,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,368,369,370,371,372,373,374,375,376,377,378,388,390,391,392,393,394,395,396)) and (`eshopuga_upgr_4122`.`cscart_category_descriptions`.`lang_code` = 'de'))",
      "cost_info": {
        "read_cost": "96.81",
        "eval_cost": "8.80",
        "prefix_cost": "105.61",
        "data_read_per_join": "146K"
      },
      "used_columns": [
        "category_id",
        "lang_code",
        "category"
      ]
    }
  }
}