Click on the Reports button on the left sidebar menu, then click the Library tab.
You can then click one of the two fields under the Expiry section to get a report showing all of the expired assets or the assets with future expiry date.
To export your data into Excel, click the three dots at the top right above the report. *See more details in this article for how to export reports.
On the Expiry report page, you can switch between the expired assets table and the expiring one.