>>48071264He heard about the break in at Silph and the raid at Lavender town and figured either Team Rocket or the cops were going to come after him in suspicion over his connection with Mewtwo/Team Rocket. He didn't hide it intentionally, the keys fell out his pocket when he escaped the explosion and they were spares he had. Blue got there before shit went down in Lavender/Saffron so the door was still unlocked.
