If you already own a valid license and need to reinstall, your options for finding the 64-bit ISO include: End of support for Office 2010 - Microsoft Support

: Choose "Install Now" for the full suite or "Customize" to select specific apps like Word, Excel, or PowerPoint. 4. Activation Post-Support

The 64-bit architecture is specifically beneficial for Excel users working with massive data sets that exceed 2GB.

: For those with a disc who need to install the 64-bit version specifically, you can find the folder on the installation root and run from there. Microsoft Support Community & Archived Downloads

Microsoft allows you to use your Office 2010 product key to install or Microsoft 365 ? No. Those are different licenses. However, if your key is from a work/school account, you might have downgrade rights to install Office 2019.