SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b50106a48a75686c8a2924d98d80ff6155e2bdf91e98b352e80687ffc2d8905' 
  AND token = 'my4CDbuJNlLEDoIsJ1pJUBl3vzWqy/fK9xY2K7Oka7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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