If you need to update a 64-bit installation of Office 2010 to its final supported state, you should download the 64-bit Service Pack 2 package directly from official sources: Service Pack 2 for Microsoft Office 2010 (64-Bit Edition)
After successfully installing SP3 on your 64-bit Office 2010, follow these final steps: Microsoft Office 2010 Service Pack 3 Download 64 Bit
As of 2023, Microsoft has removed Office 2010 SP3 from the official Microsoft Update Catalog for direct public download. However, verified static sources include: If you need to update a 64-bit installation