SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4be93669afa8cc9b3a8f9d33868551503cab81de637f86aadaa34beaa09ddf74' 
  AND token = 'URNZC9vMGMJzjAAxvblUXaR1qqeKLXmS6rby5nfGLwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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