Unless things have changed in the last few years, or AGCO is different than other tractor manufacturers, the ignition switch key should all be the same for that brand. Unlike the auto industry with a specific key for each vehicle, farm tractor, and construction ignition keys were all the same, made in certain year ranges.
I'd suggest contacting a local AGCO dealer of your choice, and check. I've personally bought extra keys for several pieces of construction equipment I operated, as late as 2005 at any dealership. 1 brand specific, Case, John Deere, or Kobelco key fit all Case, John Deere, or Kobelco machines we had. No separate key for each machine. At that time, keys were $5 each.