Not an official answer here, but this situation has not been "foreseen" when X-Plane 10 was originally launched years ago.
You might have luck with creating an .iso image of CD 1, creating a virtual drive, and using that to "unlock" X-Plane. Another way is to get a cheap USB-CD Drive.
Probably the best way is to write to customer support, they might have a solution for you. The "product-key" activation is a very recent innovation for X-Plane (after the steam-edition), so your situation is fairly new (although I am in the same boat with my new laptop).