The independent counsel whose constitutionality is under attack in the federal appeals court here has warned the court that time is running out for her to bring charges.

She urged the court "to render the expedited decision which it promised" when the case was argued in September.

Independent counsel Alexia Morrison, who is investigating possible perjury by former assistant attorney general Theodore B. Olson, asked the court to rule in a case brought by Olson and two other former high-ranking Justice Department officials challenging the constitutionality of the independent counsel law.

Morrison was appointed in June 1986 to investigate whether Olson gave misleading testimony on March 10, 1983, before a House Judiciary subcommittee probing the Environmental Protection Agency Superfund scandal.

"Serious limitations problems may thus arise if an indictment involving that testimony is returned after March 10, 1988," Morrison said. There is a five-year statute of limitations in such cases.

Morrison's warning was contained in a brief asking the court to disregard a motion by Senate legal counsel Michael Davidson last month. Davidson asked the court to consider the new version of the independent counsel law signed by President Reagan last month and the guilty verdict against former White House aide Michael K. Deaver.

She said time is of increasing concern.