I’m pretty sure it’s discontinued, I just checked and I can’t find it for sale here in the USA either. If you really want one, consider buying the standard explorer and get the Plus scales separately. Several websites offer them for around $9 for just the scales and another few bucks for the corkscrew mini screwdriver, pen, and straight pin.
Or check the used market. There are many TSA confiscated SAK knife lots. You could probably get a great deal on a used explorer plus if you search around.