He was the son of Abraham Keyser (b ca 1762) and Maria Margaretha Schaffer (b 1762), born in the part of the then district of Schoharie in Albany County which was after the creation of Schoharie County in 1797 part of the Town of Middleburgh, and was in 1828 separated as the Town of Fulton.
He was Sheriff of Schoharie County from 1815 to 1819. During his tenure occurred the murder of deputy sheriff Huddleston by John Van Alstine who was executed in 1819. Keyser appeared as a witness at the trial before Justice Ambrose Spencer.
He was a member from Schoharie County of the New York State Assembly from 1820 to 1822.
He was New York State Treasurer from 1824 to 1825, and from 1826 to 1838.
