is there a way to find out the cd key tied to this game for steam without logging into steam?

[toodamnmuch]

ive been gone 4 years or so and now i'm trying to get back into all of my old accounts and steam support is asking me to find the cd key of one of my steam games and since this game's account is one of the few i didn't lose and i did have it installed with steam i hope maybe there's some way i can find the cd key i have installed with steam.