How to go about this?

So, I’ve had my store keys for about a year. I’m the main person who closes the store when my manager isn’t in that day. Anyway, my manager and I don’t really get on. She’s very cold so I just avoid her. An older gentleman started working in the store a few months back and she’s actually given him keys for the store. She’s now getting him to close and has practically thrown me to the side when I’ve done a lot for her. He keeps boasting and bragging about the fact that he has keys and whatever. There’s times when I’d like to have the responsibility of closing the store but he’ll jump in and quickly be like ‘No! I’ll do it’.. I’m like, no honestly, I’m more than happy to close, it’s nice to take turns so one person isn’t doing it constantly. My manager is now always texting him about different things to do with the shop and I’m like, discarded. I kinda don’t want that authority anymore because I feel used in a way. How do I go about giving back my keys without sounding salty or childish?