A positive coronavirus test saw the Dane forced to self-isolate and miss their FA Cup victory at Middlesbrough on January 9 while further cases at the club saw league games with Bristol City and Reading postponed.
Frank was back at the training ground on Monday along with the rest of the squad after it was reopened and preparations for the clash with the Hatters continue, but captain Pontus Jansson will be absent after ankle surgery.
Midfielder Josh Dasilva has two more matches of a three-game ban to serve following his red card at Tottenham and Shandon Baptiste (knee) and Christian Norgaard (ankle) have struggled for game time due to their respective injuries.
Luton could hand a full debut to Kal Naismith after he impressed off the bench in the 1-0 win at Bournemouth last weekend.
Lockyer will need to be assessed ahead of the clash in London while Martin Craine (calf) is still absent.
Matty Pearson was on the bench for Saturday's match and is another in contention to start.