SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8e412288fc7990b6d40202e86bdb475019cd727a51f0a6dfbba3972e6f08bdd' 
  AND token = 'zkzHdyHSG5FL6hhqRzNVoKtmomqUJDfVW3sDjXQkzjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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