The listing, SMITE Xbox One Closed Beta has ended.
instructions here on how to redeem - https://support.humblebundle.com/hc/en-us/articles/205741858
Xbox One Closed Beta Key Redemption Instructions
Note: Beta key does not function until the Beta begins.
Click the Redeem button on the download page to reveal the code.
Copy the code.
Sign into your Microsoft account.
In the top-right corner of the page next to your avatar, hover over "My Account," then select "Redeem Code."
On the Redeem Code page, click the Redeem button.
Paste the code into the text field.
Click the Confirm button at the bottom of the screen.
After reading the message about SMITE, click the Confirm button again.
After reading the message about successful code redemption, click the Close button at the bottom of the screen.