Locked is the second winner from as many foals out of Luna Rosa (Malibu Moon), who won at three. She is a half-sister to several winners, among them Gabby's Golden Gal (Medaglia d'Oro), a multiple Grade 1 winner whose successes include the Grade 1 Acorn Stakes and the Grade 1 Santa Monica Handicap, and Always a Princess (Leroidesanimaux), a three-time Grade 2 winner who was placed in the Grade 1 Oak Leaf Stakes.

The second dam is Gabriellina Giof (Ashkalani), a dual Listed winner who was Group 2-placed and a half-sister to several winners.

The third dam Paola Quatraro (Cure the Blues) won four times in Italy. She is one of three winners out of Retrousse (Naskra), a Group 3 winner who was placed in the Premio Lydia Tesio, then a Gr.1.

Luna Rosa has a 2-year-old filly by Tiz the Law and a yearling colt by Early Voting, and was covered again by Gun Runner.