A Missouri man, who was sentenced to death for killing an elderly woman nearly three decades ago, is set to become the first person to be executed since the coronavirus pandemic was announced.   Walter Barton, 64, will die by lethal injection tonight for the slaying of Gladys Kuehler, 81, in 1991.    The execution is expected to hold despite the fact that a jury recently said that “compelling” new evidence made them feel “uncomfortable” about the conviction.   A …