Art can be subjective, but it also has objective elements as well. I haven't seen the show, but those who have have unanimously pointed out that Alison is established as the verbally precocious child of a family of readers. Having been such a child myself (which is not to claim I am in any way superior now; I just wasn't ever addressed in juvenile terms), there was nothing in Allison's use of words that struck me as out-of-character.
More importantly and whether or not Alison intuits a keyring as a symbol of lesbianism (doubtful), keys are a famous source of fascination for children from infancy on, a handy "toy" when no other is available. Alison's fascination with them makes sense on its own terms.
But keys are also rich symbols. Keys open new doors; they are the sine qua non of new directions, new possibilities. And for that reason, keys = power; and the woman with a large key ring (note that shape while you're at it) is the most powerful person in the room.
How could Allison NOT want her? Hell, now that I think about it, *I* want her! (This is a joke. No, I don't think Allison is thinking of literal intercourse yet.)