Place it right after the discovery moment in your edit, once the key is shown, then follow it with a bigger reveal cue to open the next scene. A small pop beforehand can mark the pickup, while the Inception Horn afterwards gives the new area a dramatic entrance.
关于此声音
This is a short, roughly two-second cue from Luigi's Mansion that signals an important key has been earned after finishing a section. It feels rewarding and relieved, like a small celebration after a tense hunt through the mansion. The cue comes from the GameCube game, where it marks progress and opens the way to the next area.