SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    9276, 9832, 10484, 3018, 2658, 2656, 
    4525, 3029, 2912, 3105, 2920, 7435, 
    10492, 266, 10667, 10669, 7080, 5505, 
    2653, 6552, 2917, 3024, 3535, 3539, 
    9948, 4003, 6340, 3796, 4001, 1584, 
    6536, 3532, 2910, 2722, 3648, 1936, 
    1467, 5684, 1309, 2601, 2691, 6328, 
    6473, 5340, 9697, 9947, 2763, 2849, 
    10563, 3751
  )

Query time 0.00256

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "259.08"
    },
    "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": 644,
      "rows_produced_per_join": 644,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "130.28",
        "eval_cost": "128.80",
        "prefix_cost": "259.08",
        "data_read_per_join": "3M"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (9276,9832,10484,3018,2658,2656,4525,3029,2912,3105,2920,7435,10492,266,10667,10669,7080,5505,2653,6552,2917,3024,3535,3539,9948,4003,6340,3796,4001,1584,6536,3532,2910,2722,3648,1936,1467,5684,1309,2601,2691,6328,6473,5340,9697,9947,2763,2849,10563,3751))"
    }
  }
}