A locksmith may be your best bet. Load the bike up and take it to their office to avoid the charges for them coming to you. With the VIN or the number off the lock they might be able to make a key for you.
You may call the KTM dealer and see if they know what is needed to get a new key cut. They may have access to bike info that would provide key numbers for a locksmith, if they can't do it for you. At least they could sell you a KTM key blank. Otherwise I think the locksmith will use a Triumph key blank, as I was told when getting my spare keys made that they use the same blank.
Any other way you try to get under there might be destructive. Check parts prices on the ones you might have to cut and weigh that against the locksmith quote.
Either way, get a couple of spare keys made. Keep one in the wallet and one in the house or shop.
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