I don't know whether it makes more sense to write to a church, or to the National Archives. But IMO what you should say is that you are researching the origins of two of your ancestors, Marija Bužonaitė and Martynas Zinkevičius or Sinkevičius. Martynas was born in about 1868 and Marija was born in about 1873. They probably came from the same area, which may have been Kėdáiniai. They were probably married in Lithuania in about 1890, and they emigrated in about 1890.
Marija had a brother named Jonas Bužonas who was born in about 1887 and who emigrated in about 1904 as a single man.
You want to know whether they have records regarding any of these people, what they will charge to do a search, and what they will charge to provide you with the records they find.