SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    1185, 1184, 1178, 1179, 1181, 1180, 1183, 
    1182
  ) 
  AND category_id != 265

Query time 0.00034

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": 8,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (1185,1184,1178,1179,1181,1180,1183,1182)",
      "attached_condition": "cscart_categories.category_id <> 265"
    }
  }
}