In 1973 Secretariat ran the Kentucky Derby in 1:59.40 (just under two minutes). In the history of the Kentucky Derby no horse has completed the race in a faster time. Secretariat also won the Preakness and the Belmont Stakes that same year making him the first Triple Crown winner in 25 years. At age three, Secretariat not only won the Triple Crown, he set speed records in all three races. His time in the Kentucky Derby still stands as the Churchill Downs track record for  1 1⁄4 miles, and his time in the Belmont Stakes stands as the American record for  1 1⁄2 miles on the dirt. His time in the Preakness Stakes was eventually recognized as a stakes record in 2012.

The Kentucky Derby winning times for the other horses in your choices were:

Nyquist - 2016 - 2:01.31

Affirmed - 1978 - 2:01.20

Seattle Slew - 1977 - 2:02.20

More Info: en.wikipedia.org