SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2003182211313c38457ec832718a9cf1ce1910ea2b8cf4d4f89ab0a28486f56' 
  AND token = 'u8iTFQrUW+vCZ+yEWvB9ExCPeSBnaThEgw8rQ9S912A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}