SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    5745, 5582, 6155, 5572, 5762, 5604, 6181, 
    6124, 5617, 6209, 5782, 6334, 5631, 
    6232, 5802, 5644, 6260, 5829, 5664, 
    5852, 6285, 5674, 5874, 6313, 5689, 
    5890, 5702, 5911, 5716, 5929, 5945, 
    5979, 5997, 9029
  )

Query time 0.00076

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "25.85"
    },
    "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": 62,
      "rows_produced_per_join": 62,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "13.45",
        "eval_cost": "12.40",
        "prefix_cost": "25.85",
        "data_read_per_join": "367K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (5745,5582,6155,5572,5762,5604,6181,6124,5617,6209,5782,6334,5631,6232,5802,5644,6260,5829,5664,5852,6285,5674,5874,6313,5689,5890,5702,5911,5716,5929,5945,5979,5997,9029))"
    }
  }
}