SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    545, 1091, 1092, 1093, 1094, 1095, 1096, 
    1097, 1098, 1099, 1100
  )

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": ["parent"],
      "key": "parent",
      "key_length": "3",
      "used_key_parts": ["parent_id"],
      "rows": 11,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (545,1091,1092,1093,1094,1095,1096,1097,1098,1099,1100)"
    }
  }
}