Running a light version of XP in a VM just to handle your legacy scanning station.
If you prefer a manual installation, some driver archive sites host the for Windows 10 64-bit.
To make the scanner work, you can use the original TWAIN utility or a free software like PaperScan. Easy Professor Driver for old scanner UMAX ASTRA 3450 for Windows 10
The USC 5800 cannot negotiate correctly with USB 3.0 controllers. Plug the scanner into a USB 2.0 port (usually black or white, not blue). If your modern PC lacks USB 2.0, use a powered USB 2.0 hub.