The defender moved a step closer to a first-team return following a 15-month absence with 120 minutes at the b2net Stadium on Wednesday.
But the day was tinged with disappointment as the League Two leaders were beaten on penalties, with Lowry missing one of Chesterfield`s spot-kicks.
The Spireites looked to be cruising into the competition's semi-finals when goals from Dean Smalley and Jordan Bowery gave them a 2-0 lead but Derby responded with two goals in two minutes late on to set up extra time.
The Rams went ahead from the penalty spot but Jordan Burrow equalised to make it 3-3 and send the tie into a penalty shoot-out, which Derby won 4-1.
Source: PA
Source: PA