Plymouth replied with Jamie Mackie shooting wide when well-placed but still Wolves pressed forward and Keogh could not quite reach a cross-shot from Kightly.
Eastwood replaced Keogh with 25 minutes left but only had one chance which he pushed wide of the post.
The game was delayed by several minutes after a nasty-looking injury to Plymouth captain Krisztian Timar, who was stretchered off.
Olofinjana finally broke the deadlock and the teams played eight minutes of added time but Wolves could not find the two more goals they needed to overhaul Watford and snatch the final play-off spot.
It was a disappointing finish to the season for Wolves, who reached the play-off semi-finals last season.
However Plymouth will be pleased with their 10th-placed finish, one place above last season.
Wolves boss Mick McCarthy:
"If we'd nicked it 1-0 I guess we would not be feeling so bad, but we haven't, we've had loads of chances and not managed to score three goals.
"That one game has been a reflection on the 46 this season when we have been dominant and not scored.
"But the lads have worked their socks off and we have had 19 clean sheets."
Plymouth boss Paul Sturrock:
"Our goalkeeper can't think of a save that he's had to make.
"He's finished up with the one chance through the middle and other than that I don't think there's anything he has had to make an incredible save from."
On Timar's injury Sturrock added: "We don't know how serious it is, he has been rushed to hospital but it doesn't look good. It would be unprofessional for me to guess what it is so we will wait to see what the specialists come back with."
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