SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9868589421d9e25e7683232d357b4055b76697c9b1af5a5b8586260bf86ac0c8' 
  AND token = 'rSO1xDIZ1dv4lEZfehAvbfw2PGXlOGO/zXwmUXHqKl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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