Key attended Hapeville Charter Career Academy in Union City, Georgia.

[7] As a junior in 2017, Key was limited to 8 games due to injury, but finished with 33 tackles, 4 sacks, and a forced fumble.

[8] Prior to Key's junior season, he was projected as the number one overall prospect for the 2018 NFL Draft by Chris Trapasso of CBS Sports.

[12] In January 2018, he was ranked as the number two draft prospect at the outside linebacker position, behind Tremaine Edmunds of Virginia Tech, by Mel Kiper of ESPN.

[13] Key was projected to be an early first round selection, but his off-the-field issues caused his draft stock to plummet.

[16] After having two sacks in his final two games, Key suffered a broken foot and was ruled out the rest of the season.

[20] On December 26, 2020, in a Week 16 home game against the Miami Dolphins, Key committed a 15-yard personal foul penalty when he grabbed the facemask of Dolphin QB Ryan Fitzpatrick on a play where the Dolphins gained 34 yards; the penalty and catch put Miami in field goal range and Miami hit one from 44 yards to earn a 26-25 win, which eliminated the Raiders from playoff contention.