The rusted key unlocks a shack on the roof of Freddy Fear's House of Scares in the northern Mire. In order to get to the key to open it, one will have to go to a submerged safe with the alien blaster and a rusted key, which will begin an unmarked quest:
When using an alien blaster with a standard magazine, alien blaster rounds will drop as contextual ammo from Daily Ops.The rounds consist of a cylinder of blue energy capped at each end by metal disks. The alien blaster round is a type of ammunition in Fallout 76.
