SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8247be6043f9528c1abea83c94f3182663758bda0d74ef69429942239c3165cf' 
  AND token = 'Keu+AUl6ID44MkNLGb8jHZ0OUcxVuQRhtHHpHzjRVaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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