Openda struck three times within four minutes, 30 seconds during Sunday's match. According to stats provider Opta, that was four seconds quicker than Matt Moussilou's treble in Lille's 8-0 rout of Istres in April 2005.
Lens trail second-placed Marseille by two points and are three points clear of Monaco.
Openda had not scored in his 11 previous games but he rediscovered his touch by slipping the ball through the legs of goalkeeper Mory Diaw in the 31st minute.
He then closed down Clermont midfielder Maxime Gonalons, who lost possession to Adrien Thomasson in the 34th. A selfless Thomasson set up Openda, who doubled the lead with a low strike.
The Belgian striker then intercepted a poor back pass from Mateusz Wieteska to round Diaw in the 35th and slot into an empty net for his 12th league goal this season.
Lens substitute Alexis Claude-Maurice sealed the win in the 76th with a goal set up by Openda.
In other games, Strasbourg midfielder Jean-Eudes Aholou scored two late goals to salvage a 2-2 draw with 10-man Marseille.
Aholou pulled one back in the 88th after the Marseille defence failed to clear a corner. A minute later, he equalised with a long-range striker. He nearly got his hat-trick in stoppage time but Marseille goalkeeper Pau Lopez saved from close-range.
Marseille were down to 10 men in the 29th minute when Leonardo Balerdi was sent off for bringing down Strasbourg striker Habib Diallo.
Chancel Mbemba scored in the 49th after Strasbourg goalkeeper Matz Sels had palmed away a free kick from Ruslan Malinovskyi.
Alexis Sanchez added a second goal with a penalty in the 76th after Strasbourg defender Frederic Guilbert fouled him.
Monaco lost ground in the race for the Champions League spots with a 1-0 defeat to Reims as English striker Folarin Balogun notched his 16th league goal by scoring in the 51st.
Monaco hit the woodwork twice. Wissam Ben Yedder's chip bounced off the post in the 30th while Vanderson's strike hit the base of the post in the 50th.
Reims extended their unbeaten run to 19 games to pull within four points of the European spots. Monaco drop to fourth.
Nice missed an opportunity to make up ground as they twice wasted the lead in a 2-2 draw with Nantes to stay seventh.
Nigeria forward Terem Moffi opened the scoring with a header in the fifth minute before Nantes midfielder Moussa Sissoko leveled by heading home a free kick in the 31st.
Burundi defender Youssouf Ndayishimiye thought he had given Nice the win with a low strike in the 71st but Nantes substitute Mostafa Mohamed equalised with a powerful header in the 88th.
Lorient went level on points with Nice by beating Troyes 2-0 with goals from Senegal forward Bamba Dieng in the ninth and substitute Stephane Diarra in stoppage time.
Midtable Toulouse snapped a three-game losing streak by defeating bottom-side Angers 2-0 with goals from Danish right back Mikkel Desler in the 37th and Dutch striker Thijs Dallinga in the 47th.
Montpellier beat struggling Ajaccio 1-0 with a goal from substitute Elye Wahi in the 68th.
On Saturday, Paris Saint-Germain edged Brest 2-1 to extend their lead to 10 points.
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