How do take cheap keys and make them look older with darkened areas. I don’t want them shiny.
Here's a good tutorial: http://treasuresfromtheheartgifts.blogspot.com/2012/07/rust-and-patina-how-to.html
Try a mixture of vinegar and sea salt. Allow the items to soak for 30 minutes. Check and allow more time as needed.
Aluminum or steel----lay them out on plastic, spray with oven cleaner(yellow can) or use gel toilet bowl cleaner(ZEP brand) or just straight Lye(cheap at Acehardware) let sit in solution in sun until they look how you want them(this darkens them/oxidizes) you'll need to sand or buff with steel wool to remove oxidation /highlight them Brass https://inmyownstyle.com/how-to-age-brass-in-less-than-5-minutes.html
Mix steel wool in a jar of vinegar and throw them in over night.