SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7704d686d2b1a3636cf4fa47cd83bb835274c95c7fce075c6412892e6c5d7c54' 
  AND token = '8dIVxLZht8oCJanKHsp5iVnpjn/gB+WI6Il8leGpYvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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