Yeah, I went thru that a couple years back. I looked in all the suggested places, trunk hinge, glove box, even the main computer. Nothing. Either you have the little card in the owner's manual or you pay the dealer $$ to read the code and then WRITE IT DOWN somewhere so you or the next owner will have it.
By the way. If you only have 2 keys you should get a copy made right away. Copies REQUIRE you to already HAVE 2 working keys. If you have one key, only the dealer and some special lock smiths can make a duplicate. If you loose the only key you have, you will have to be towed to a dealer so they can program a new set for you.
The keys have to be matched to the car so that is why you must have at least one working key to make duplicates. Could be worse, some cars have $1,000+ keys. Ours can be bought on eBay relatively cheap.
Good Luck,
Jim Henderson