UPDATE [DB].[dbo].[OrigKeys]
SET [DB].[dbo].[OrigKeys].[Key] = [TS2].[Key]
FROM [DB].[dbo].[BackupMachine] AS TM2
    INNER JOIN [DB].[dbo].[BackupKeys] TS2 ON [TS2].[Id] = [TM2].[Id]
    INNER JOIN [DB].[dbo].[OrigMachine] TM1 ON [TM1].[Name] = [TM2].[Name]
WHERE [TM1].[Name] = [TM2].[Name];