Dumbarton spent much of the first half with their backs to the wall but took a shock lead four minutes from the break when Craig Barr scored with a header.
Kilmarnock equalised shortly after the break when Mikael Ndjoli beat Grant Adam with a crisply-struck shot into the far corner of the net.
Bobby Barr put Dumbarton back in front but substitute Boyd, on the pitch for barely a minute, netted his first goal of the season to bring Kilmarnock level again. Boyd did not have long to wait for his second goal as he headed Killie in front before completing his hat-trick late on.
Elsewhere in the group, Queen’s Park edged Spartans 2-1 at Hampden. After an evenly-matched first half, in-form Spartans took the lead when Jamie Dishington scored but Scott Gibson cancelled out the goal moments later with a neatly-placed header.
Curtis Roberts gave Queen’s Park the win with a superbly-struck shot into the top corner of the net.
In Group F, Airdrieonians won handsomely, 3-0 at Berwick Rangers. Sean Crighton, pictured, headed them in front after 20 minutes when he met Ryan Conroy’s corner at the back post to break the deadlock. The Lanarkshire side doubled their advantage when Darryl Duffy slid the ball home nine minutes from the break. Duffy came within inches of making it 3-0 within seconds of the restart when his shot struck the inside of the post.
It was left to Leighton McIntosh to seal the points with 14 minutes left to play.
In Group G, Motherwell were held to a 1-1 draw at Stranraer. The Steelmen took time to find their feet but skipper Peter Hartley gave them the breakthrough minutes from the interval.
Stranraer refused to lie down and Isaac Layne scored a deserved equaliser after 59 minutes and they went on to win the penalty shoot-out 3-2 after a remarkable SEVEN misses from the spot.
Tony Watt scored his first goal as St Johnstone beat a decent Montrose team 1-0 in Group B as he looks to make an impact for his new club.
In Group E, Ayr United comfortably won 2-0 at Albion Rovers with Alan Forrest scoring in the first half and Steven Bell heading the clincher late on in a dominant display.
Morton eased to a 2-0 home win over Stenhousemuir. Ross McLean opened the scoring when he calmly rounded the goalkeeper to find the net and Bob McHugh headed home a Michael Tidser cross shortly before half-time.
In Group A, Arbroath beat Elgin City 2-0. After a goalless first half, Colin Hamilton put Arbroath in front and a late goal from Thomas O’Brien secured the points.
Cowdenbeath edged Cove Rangers 1-0 in Group C thanks to a late goal from David Cox after Jordyn Sheerin’s shot had come back off the post.
Stirling Albion ended their long spell without a win when they beat Peterhead 2-0 at Balmoor in Group D. Peter MacDonald gave Stirling an early advantage and Mark Stewart doubled their advantage with 19 minutes left.