SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '926d23c9939dd2fb410b3f354b2f3fa17a4798b5143a542b22618f351c356e27' 
  AND token = 'Xid8VrrplT7QwmKULLESbE51lICbTMmmfDyKrrn/LE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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