The Falcons took possession with 16.2 seconds left in the game, as the ball was inbounded to Catherine Davis at the half-court line.
Davis was fronted by two defenders and passed to center Samira Seraji, who came out toward the three-point line.
Seraji looked for a teammate to pass to as the clock wound down to about six seconds.
That's when Seraji fed Mirzaian eight feet from the basket with 5.6 seconds left.
Mirzaian pushed around her defender, spun and lobbed in the game-winner.
That score was the final of three lead changes over the last two minutes with Culver City (4-3) leading 54-51 after senior guard Jade Neal hit a deep two-pointer to put the Centaurs up, 54-51, with 1:30 remaining.
The Falcons answered, though, with a pair of free throws from sophomore Ella Stepanian, followed by a steal from Davis on Culver City's next possession that translated into a layup from Mirzaian with 58.2 seconds left that put the Falcons up 55-54.
The Centaurs quickly countered with a 10-footer from Markie Samler with 43.6 seconds remaining that came on the heels of a Falcons miss the other way, which put the ball in Culver City's hands, up, 56-55, with 32 seconds left.
Twelve seconds expired before Davis fouled Culver City's Taylor Tanita and Tanita missed the front end of a one-plus-one bonus situation, which was rebounded by Seraji as Falcons Coach Jason Perez called a timeout with 16.2 seconds left.
"We actually had a lot of options on that final play," Perez said. "There was a give-and-go to Catherine, there was a down screen for Ella to curl off of, there was a cross pick for Catherine and we went through all our options before Lexi took control on that final play."
The Centaurs took their biggest lead at 31-24 with 6:15 in the third on a sweeping layup from Tanita.
However, Crescenta Valley closed the gap to 38-37 with a clutch three-pointer from Davis as the shot clock expired with 33.3 seconds left in the third.
Culver City led, 40-37, to start the fourth, but lost its grip when the Falcons started the quarter with a 10-2 run to take a 47-42 lead with 5:45 left on a rebound and putback by Stepanian.
The Falcons' rally was fueled by five Centaurs' turnovers (four forced) over six possessions.
Stepanian led all scorers with 22 points and four steals, while Davis added 11 points and seven assists.
Neal paced the Centaurs with 21 points, while Samler added 15 points and Tanita chipped in 11 points.