SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    2913, 3018, 2916, 2915, 2944, 3007, 3011, 
    3080, 2912, 3105, 2920, 3362, 3691, 
    3408, 3251, 3006, 2933, 2921, 2914, 
    4029, 5522
  )

Query time 0.00070

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "95.58"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 236,
      "rows_produced_per_join": 236,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "48.38",
        "eval_cost": "47.20",
        "prefix_cost": "95.58",
        "data_read_per_join": "1M"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (2913,3018,2916,2915,2944,3007,3011,3080,2912,3105,2920,3362,3691,3408,3251,3006,2933,2921,2914,4029,5522))"
    }
  }
}