SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21786ac5c1d23894266749f27a35333bda682b7c4b1620b106f932b214528606' 
  AND token = 'Qg5N8sNENlDCKYbDqRsmIhPaRenkpluFfSGkGx2NuFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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