SELECT 
  id_path 
FROM 
  cscart_categories 
WHERE 
  category_id IN (
    337, 338, 339, 340, 345, 349, 350, 351, 
    353, 358, 359, 361, 362, 363, 369, 370, 
    374, 377, 378, 379, 390, 391
  )

Query time 0.00081

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.02"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "ALL",
      "possible_keys": [
        "PRIMARY",
        "p_category_id"
      ],
      "rows_examined_per_scan": 115,
      "rows_produced_per_join": 21,
      "filtered": "19.13",
      "cost_info": {
        "read_cost": "23.62",
        "eval_cost": "4.40",
        "prefix_cost": "28.02",
        "data_read_per_join": "58K"
      },
      "used_columns": [
        "category_id",
        "id_path"
      ],
      "attached_condition": "(`eshopuga_upgr_4122`.`cscart_categories`.`category_id` in (337,338,339,340,345,349,350,351,353,358,359,361,362,363,369,370,374,377,378,379,390,391))"
    }
  }
}