SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    8175, 8199, 8203, 8228, 8230, 8240, 8249, 
    8250, 8253, 8276, 8280, 8295, 8311, 
    8334, 8339, 8340, 8347, 8380, 8391, 
    8415, 8422, 8445, 8279, 8301, 8495, 
    8300, 8268, 8474, 8508, 8337, 8371, 
    8502, 8501, 8507, 8344, 8473, 8462, 
    8447, 8566, 8518, 8316, 8419, 8477, 
    8478, 8275, 8616, 8615, 8418, 8656, 
    8657
  )

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.37"
    },
    "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": 50,
      "rows_produced_per_join": 50,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "5.37",
        "eval_cost": "5.00",
        "prefix_cost": "10.37",
        "data_read_per_join": "129K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (8175,8199,8203,8228,8230,8240,8249,8250,8253,8276,8280,8295,8311,8334,8339,8340,8347,8380,8391,8415,8422,8445,8279,8301,8495,8300,8268,8474,8508,8337,8371,8502,8501,8507,8344,8473,8462,8447,8566,8518,8316,8419,8477,8478,8275,8616,8615,8418,8656,8657))"
    }
  }
}

Result