“It cannot wait,” says the Rev. Martin Luther King Jr. in the civil rights movie Selma, which opened nationwide last Friday. King is pleading with President Lyndon B. Johnson to sign the Voting Rights Act. It’s a trenchant scene whose message is not lost on Rep. John Lewis, D-Ga., who is also depicted in the film. Lewis, now 75, is still an idealistic agitator whose sense of urgency for dismantling discrimination has long extended to gay rights.