How can I find all *old* Keynote presentations on my computer? I have some old Keynote presentations. When I try to open them with the latest Keynote (6.5.2 (2119)), I get the following warning:

This presentation can’t be opened because it’s too old.
To open it, save it with Keynote ’09 first.


I've managed to get Keynote '09 installed, and I can open with that, save, open with the current version, and save again. 

It will be a pain to do this with all of my Keynote presentations, but it seems it has to be done if I want to be able to access them in the future. Or I should convert them to PDF so they are in a format with more long-term access options.

How do I find all of the Keynote presentations on my computer that are outdated? Is there an mdfind option that will allow me to find just the old versions?
A Smart Folder is probably the easiest way to find all your old Keynote files. To create one:


Open a Finder Window
Click "File" > "New Smart Folder"
In the search box, type "key" and then select "Keynote Document" from the dropdown
If you like, you can add a last modified filer by clicking the "+" sign under the search box.
If you want to save the Smart folder, click the "Save" button