SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a77b75115a093468bcc1659756d99a05064c53ee43cd33d47de5f10bbdbae3f' 
  AND token = 'LK8Bu6DraxsRTiXpbQY+IQ0lRCKKnnr4XKv7upMRcz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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