I've bought a Hanimex 1:4.5, 80-200mm Automatic Zoom lens. The seller wrote that it is a Minolta MD-mount lens, but it doesn't fit my Minolta x300. What mount is this lens?
Your lens likely has a Canon FD mount. The reasons are as follows:
You can confirm the mount by attaching the lens to a camera with an FD mount.
The pin on this lens is not longer than the pin on any other FD-mount lens. It only appears longer because of perspective:
Here is the pin from a new-FD mount for comparison.
It seems unlikely that not having a moving mirror would allow the Pellix to be able to take a longer pin. The mirror in FD mount lenses is above the aperture-control linkage. Whether the mirror is present or moving does not affect how long the pin can be.