No, at least for prosecution. A guy got off the hook years ago after they caught him at TSA (TSA predecessor?) by claiming that he showered, shaved, and put on the uniform because he was going to the airport to use the ops landline to call in unfit. Judge tossed the DUI due to reasonable doubt, maybe it was before cell phones were ubiquitous.

Same as if you walk out of a bar with car keys in your pocket or hand... doesn't count unless you open the driver's door. That one's been litigated too.

That's for US though, Euro laws might be different, they seem to be leaning into thought crimes these days.