mysql - NOT IN サブクエリの実行に時間がかかりすぎる

Question

このクエリを最適化して、それほど時間をかけずに同じ結果を得るにはどうすればよいですか? NOT INサブクエリには非常に長い時間がかかります。

SELECT DISTINCT EmployeeId FROM employees
    WHERE 
    status = 'Active' 
    && BranchId = '2' 
    && NOT EXISTS (
      SELECT * FROM attendance
      WHERE
      employees.EmployeeId = attendance.EmployeeId 
      && attendance.AttendanceDate = '2015-01-20'
    )
  )

SELECT EmployeeId FROM employees 
    WHERE 
    status = 'Active' 
    && BranchId = '2' 
    && NOT IN (
      SELECT EmployeeId FROM attendance WHERE AttendanceDate='2015-01-20'
    )