Legal Question in Criminal Law in Michigan

In theory, yes. The issue is whether all the facts (what people see and hear, what you are doing, etc., and the inferences that can be drawn from all of that) prove beyond a reasonable doubt that you were "operating the vehicle" ... meaning that you were in actual physical control of it. (Michigan changed from "driving under the influence" to "operating under the influence" more than 20 years ago in response to several appellate cases where defendants had been found 'parked'.) The test is not as simple as "the ignition was on/off" or "the key was in/out of the ignition". Since you didn't tell us anything more about the case details, it's hard to give a more specific answer than that. I would guess that some important additional information may include whether there's evidence that the car had just been driven TO that parking spot (e.g., engine is warm, eye witness or security video shows this, etc.) and that you were the one who just drove it there ... or what the evidence shows you had been doing in the car before police found you (literally sleeping in the back seat, or sitting in the driver's seat?) ... or whether the car keys were in your pocket in the car vs in the purse of the car owner who was inside the store's rest room (i.e., the vehicle could not HAVE been operated/driven/moved so there was an 'impossibility' issue) ... or ... etc., etc., etc. The bottom line is that the unique case facts need to be assessed by YOUR defense attorney, who will know your detailed knowledge of the facts + the police and eye witnesses' information, and then be able to assess if you have a legal or factual defense.