Stevens belted five sixes and six fours in a 32-ball knock as Kent posted a healthy 175/6. Openers Denly made run-a-ball 27 while Key a sedate. Azhar Mahmood (25* off 13) played a gem of an cameo down the order.
In reply Warwicks were limited to 133/8 despite the fighting effort from the batters in middle-order-Darren Maddy (27 off 18), Ant Botha (35 off 19) and Troughton (22 in 15). Pak seamer Yasir Arafat was the pick of Kent bowlers with 3/29.
Earlier, put in to bat, Kent crawled to 60/3 half way thro' their innings, thanks to tidy spell by Kiwi pacer Chris Martin before Stevens freed his arms against the change bowlers.
Botha, who reined in Stevens was surprisingly taken out of attack and was replaced by pedestrain Tim Groenewald.
That was the signal for Stevens to attack and he lifted Groenewald for two sixes in an over that cost 22 runs. Worse was to follow when Chris Woakes was brought back by Maddy at the City End. After three legitimate balls the England U-19 seamer's fourth over had cost 26 when he was ordered out of the attack by umpire Rob Bailey for bowling two beamers - but not before Stevens had pummelled him for three maximums.
Maddy had to complete the over and though he bowled Stevens with his first ball the damage had been done.
The over, the 19th of the innings, cost 33 runs and Stevens' onslaught helped Kent plunder 99 from their last six overs. Stevens added 60 for the sixth wicket in just three overs with Azhar Mahmood.
The Pakistani pace duo of Azhar Mahmood and Arafat made Warwicks batters struggle with a probing line. Neil Carter, often their danger man in the group stages, was bowled by Yasir Arafat in the second over for two and anchorman Jonathan Trott (13) soon holed out to mid-on as Warwicks slumped to 42/3 before drifting quietly to defeat in front of a measly (6000) home crowd.
Kent 175/6 in 20 (Darren Stevens 69, Joe Denly 27, Azhar Mahmood 25 n o; Chris Martin 1/15, Ant Botha 1/14, Niel Carter 1/16) beat Warwickshire 133/8 in 20 (Ant Botha 35, Darren Maddy 27, Troughton 22; Yasir Arafat 3/29, Stevens 2/29).