SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    8151, 8152, 8229, 8230, 8231, 8249, 8232, 
    8233, 8234, 8235, 8236, 8153, 8237, 
    8238, 8239, 8240, 8241, 8242, 8243, 
    8244, 8245, 8246, 8247, 8248, 8066, 
    8112, 8113, 8114, 8115, 8116, 8117, 
    8118, 8119, 8120, 8121, 8122, 8123, 
    8124, 8125, 8126, 8127
  )

Query time 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "18.24"
    },
    "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": 43,
      "rows_produced_per_join": 43,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "9.64",
        "eval_cost": "8.60",
        "prefix_cost": "18.24",
        "data_read_per_join": "254K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (8151,8152,8229,8230,8231,8249,8232,8233,8234,8235,8236,8153,8237,8238,8239,8240,8241,8242,8243,8244,8245,8246,8247,8248,8066,8112,8113,8114,8115,8116,8117,8118,8119,8120,8121,8122,8123,8124,8125,8126,8127))"
    }
  }
}