Joy Baker proposed a toast at the Motion Picture Association of America luncheon in her honor yesterday.

"To the president of the United States, past presidents of the United States . . ." She paused. "And to future presidents."

Baker's husband, Howard, the Senate majority leader, has announced he doesn't intend to seek reelection after his term ends in 1984, leading people to believe he may be planning to run for president. Joy Baker addressed that issue.

"Just in case you're thinking that two years from now you won't see me--don't believe it," she said. "We'll be around Washington in some capacity."

Baker said during the chatty, casual annual luncheon that she and her husband plan to tear down part of their 30-year-old house in Huntsville, Tenn., to build a much larger one. "Our son, Darek, and his wife are expecting twins, so we're going to need a lot more room for visitors." Darek is chief programmer for Federal Express in Memphis, Baker said.

"He's the one who never cared about politics. But everyone's speculating on who's going to run for Howard's seat. They've been asking Darek if he's going to run. He just grins and says, 'I'll have something to say after April 5. Why April 5? I'll be 30 then.' " (That's the minimum age for a senator.)

Baker said her daughter, Cynthia (Cissy), who just lost an election for a House of Representatives seat from Tennessee, is working for Cable News Network and isn't old enough to run for the Senate. Then she and Jack Valenti, MPAA president, began a conversation about the shortage of Washington men available as prospective husbands for women Cissy's age (26) and abilities (multifaceted). "Not an actor," said Valenti. "They're the worst kind."

Nancy Thurmond, wife of Sen. Strom Thurmond and one of the chairwomen of the luncheon, paid tribute to Joy Baker, who was celebrating both her birthday last week and her recuperation from a recent operation. "Joy Baker, you're the sweetheart of the Senate. We admire you for your grace and intellect. We respect you for your calm and dignity, and we love you because we can't help it."

Valenti, in his remarks, said he was all in favor of Joy Baker but he hadn't always had an easy time with her father, the late Senate minority leader, Everett Dirksen. When Valenti was President Lyndon Johnson's special assistant, he said, "I was assigned to keeping longtime Senate leader Dirksen happy.

"Dirksen used to call me and say, 'I need to see Lyndon.' We'd set up a time. Then Dirksen would get up in the Senate and compare Lyndon unfavorably to Caligula, the Roman despot. Johnson would say, 'Everett, you're terrible.' Dirksen would reply, 'You know I have to speak the truth.' Then they'd sit for hours at the White House together, practically knees touching, and they'd settle on four appointments and eight pieces of legislation. And they'd be very late for dinner."

Nancy Thurmond saluted all the guests as "survivors of the storm. After being cooped-up with four children, the dogs and all the neighbors' children, I can't believe I'm not in St. Elizabeths."

Before the luncheon (baked crab casserole, salad, ham, sesame rolls, petits fours and white wine), Erma Byrd said her husband, Senate Minority Leader Robert Byrd, had to dig their car out at their McLean home. "Just when he and the sons finished moving the snow to clear the way, the snowplow came by and covered it all up again."

Barbara Pryor, a cohostess for the 50-guest buffet, said Valenti's wife, Mary Margaret, "isn't here because she knew we'd gush over Jack. This is our favorite party of the year, because Jack does all the work, it's just for fun, there's no politics and no protocol. Though several of us didn't know how to sit down without place cards and a list."

Other guests, mostly Senate wives and Washington socialites, around the round tables in the MPAA dining room included Carolyn Long, Pennie Durenberger, Mary Frances Smoak, Caroline Mattingly, Georgie Packwood, Mary Sasser, Esther Coopersmith, Gretchen Byrd, Sally Gorton and Mary Johnston.

After the lunch, the guests saw Jon Voight in "A Table for Five." Valenti said, "If you do like it, tell everybody. If you don't, don't leak it."