The Catalans went into the game 10 points in arrears of leaders Real Madrid and appeared set to squander the opportunity to close the gap on their rivals when David Barrall cancelled out Andres Iniesta's first-half strike just moments after Blaugrana defender Gerard Pique had been sent off for a professional foul.
However, Keita put Barca back ahead with a superb curling effort with just 11 minutes to go before Xavi sealed victory for Pep Guardiola's men by chipping in with a third right at the death.
“I’m very pleased because it was very important to win," the midfielder was quoted as saying by his club's official website.
"We were ten points down so the league would have been lost [had Barca not won]. We could have drawn but, in the end, we won the three points."
Addressing the ongoing speculation over Guardiola's future with Barca, Keita revealed that he is in no doubt that the former Spain international will sign another one-year extension.
"This is their home and this is his family," the Mali international is quoted as saying by Sport. "I'm sure Pep will remain here."
Keita, who joined Barca from Sevilla in 2008, has been linked with a move away from Camp Nou at the end of the season.
Since November, Goal.com has been publishing exclusive extracts from Graham Hunter's highly-anticipated new book, 'Barca: The Making of the Greatest Team in the World'. The very last extract, which was published last Friday, looks at Andres Iniesta's risky return from injury in the 2009 Champions League Final and how he was described by Wayne Rooney as the 'best midfielder in the world'. Don't miss it!