Key was born on April 4, 2002. He was raised in Bay Shore and went to Brentwood HS through his sophomore season and to Long Island Lutheran High School in Brookville, New York as a junior and senior. With teammate and future Illinoispoint guardAndré Curbelo, Long Island Lutheran was one of the best high school programs in the country. In his junior season, Long Island Lutheran won the New York Class AA state championship. He averaged 18 points and 8.7 rebounds in his senior season. In wins over national powerhouses Sierra Canyon High School and The Patrick School, Key had standout performances, scoring 25 and 37 points, respectively.
Key was rated as a three and four-star recruit and ranked as the fourth best player in New York. On September 22, 2019, Key committed to Ohio State over offers from teams such as Florida, Illinois, and Wisconsin.
Key started his college career off the bench during his freshman year, averaging 5.2 points and 3.4 rebounds per game. He played in all 31 games and totaled 22 blocks, trailing only E. J. Liddell on Ohio State. In a win over Cleveland State, he earned a double-double, scoring 12 points and pulling down 10 rebounds.
In his sophomore season, Key became a consistent starter. He scored a career-high 20 points as an unranked Ohio State upset Duke at home. Overall, he averaged 7.8 points and 5.4 rebounds per game in 23 starts for the Buckeyes.
