SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    1165, 1166, 1156, 1167, 1157, 1168, 1169, 
    1170, 1158, 1171, 1172, 1173, 1153, 
    1174, 1159, 1160, 1161, 1175, 1176, 
    1154, 1155, 1163, 1164, 1162
  ) 
  AND category_id != 265

Query time 0.00056

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "parent", "p_category_id"],
      "key": "parent",
      "key_length": "3",
      "used_key_parts": ["parent_id"],
      "rows": 40,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (1165,1166,1156,1167,1157,1168,1169,1170,1158,1171,1172,1173,1153,1174,1159,1160,1161,1175,1176,1154,1155,1163,1164,1162)",
      "attached_condition": "cscart_categories.category_id <> 265"
    }
  }
}