After creating a backup,
Step 1
On Windows, open the Run dialog with [Windows]+R and fill in "%APPDATA%\Apple Computer\MobileSync\Backup\" without the quotes and press [Enter].
On macOS, open Finder, open the Go dialog with [Shift]+[Command]+G and fill in "~/Library/Application Support/MobileSync/Backup/" without the quotes and press [Enter].
Step 2
Open the most recent folder shown after Step 1, which should have a name with numbers and letters. Inside that folder, you should see the files
3d0d7e5fb2ce288813306e4d4636395e047a3d28 and 31bb7ba8914766d4ba40d6dfb6113c8b614be442.