MasterCard Inc. said profit and revenue rose in the first quarter as card users spent more. Profit of $766 million, up 12 percent, beat the forecasts, though revenue missed despite having risen 8 percent to $1.9 billion. Company executives sketched a picture of a mixed global economy and a US consumer suffering from January’s payroll tax hike. The US economy ‘‘was definitely very choppy,’’ CFO Martina Hund-Mejean said. She expects the current quarter to be unsettled, too.