SELECT 
  updated_timestamp 
FROM 
  cscart_absolute_rating 
WHERE 
  `object_type` = 'company' 
  AND `object_id` = 1

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_absolute_rating",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "102",
          "used_key_parts": ["object_id", "object_type"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}