The easiest method would be to validate the file immediately after opening.
Once done, you can check first and if it is the wrong file, you can close it and stop executing:
MyFilePath = Application.GetOpenFilename()
Set MyWorkbook = Workbooks.Open(MyFilePath)
If MyWorkbook.Worksheets(1).Range("A1") <> "Archive" Then
MyWorkbook.Close
Exit Sub
End If