A Queens teenager who confessed to shouting racial slurs last summer as he attacked two Asian men and struck one with a car steering lock was sentenced yesterday to more than three years in prison on felony hate crime assault charges. Kevin Brown, a 19-year-old parking valet who pleaded guilty in January, was involved in another assault in which he admitted beating a man with a hammer. The other man involved in the attack, Paul Heavey, will be sentenced today. The Queens district attorney, Richard Brown, who is not related to the felon, condemned the attack as “cowardly” and an “affront to civilized society.”