On 12 March 2005, at age 80, he became the oldest sub-7 miler in history at the USA Masters Indoor Track and Field Championship (Jacksons Track, Nampa, Idaho), running it in 6:48.02. However, although this was set at a US championship, and was more than a minute faster the previous indoor record set by American Henry Sypniewski, who ran the mile in 7:51:9 at age 81 in June 2000, it was not ratified as an American record (see American records). The M80 world mile record has subsequently been improved by the Spanish runner Manuel Alonso Domingo, who ran 6:22.69 in 2017 (see List of world records in masters athletics). On 14 May 2005, Keston ran the mile in 6:48:2 in the Fountain of Youth Masters Mile at Canby High School, Canby, Oregon, but this was also not ratified as an American M80 record (see American records). At the same meeting, he also ran 3000m in 13:30:77, which was faster than the officially ratified American M80 record set by Ed Benham in 1990 (although Benham had run a faster time, never officially ratified, in 1989).