The Vanished Keys

I've been in search for my car keys for 3 days now. I have absolutely NO idea where they could possibly be. I know that I used them on Saturday to drive us home after we went on a hike, but after that they just all of a sudden vanished. I have a suspicion that Lyndsey may have them somewhere. When we were in Portland, I bought these key cover things that make the top of the key look like a monkey. Lyndsey truly enjoys that part and always points out that I have two monkeys on my keys.
In a past situation it has been the mysterious lost cell phone. Lyndsey was probably 13 months in this particular instance. I asked her if she knew where Mommies cell phone was. Sure enough she walked right over to her toy box, dug through a few things, and handed over my phone. Unfortunately, Lyndsey now answers all questions with "I don't know".
So, if anyone has any clue on where I should look next, let me know. I think I'll dig through the toy box tomorrow.