SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    3087, 3390, 2916, 2944, 3080, 2912, 3105, 
    2920, 3741, 3224, 3407, 3228, 3231, 
    3002, 3085, 2917, 6579, 3095, 5522, 
    3144, 2954, 3060, 3046, 3185, 2985, 
    3048, 3487
  )

Query time 0.00131

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "118.42"
    },
    "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": 293,
      "rows_produced_per_join": 293,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "59.82",
        "eval_cost": "58.60",
        "prefix_cost": "118.42",
        "data_read_per_join": "1M"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (3087,3390,2916,2944,3080,2912,3105,2920,3741,3224,3407,3228,3231,3002,3085,2917,6579,3095,5522,3144,2954,3060,3046,3185,2985,3048,3487))"
    }
  }
}