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
  ) 
  AND lang_code = 'de'

Query time 0.00072

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "48.01"
    },
    "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": 20,
      "rows_produced_per_join": 20,
      "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)) and (`eshopuga_upgr_4122`.`cscart_category_descriptions`.`lang_code` = 'de'))",
      "cost_info": {
        "read_cost": "44.01",
        "eval_cost": "4.00",
        "prefix_cost": "48.01",
        "data_read_per_join": "66K"
      },
      "used_columns": [
        "category_id",
        "lang_code",
        "category"
      ]
    }
  }
}