Nodejs is slow to load mysql data

I am using angularjs and nodejs with MYSQL but when I get the list from the MYSQL table it is too slow to load the data about 30 seconds n load the list, what can I do to optimize this time?

Then I leave my code

var myApp = angular.module('angularTodo', ['angularUtils.directives.dirPagination']);


myApp.controller('mainController', ['$scope','$http', function($scope, $http){

   $http.get('/api/todos').then(function(res) {
       $scope.pacientes = res.data;
       $scope.sort = function(keyname){
               $scope.sortKey = keyname;   //set the sortKey to the param passed
               $scope.reverse = !$scope.reverse; //if true make it false and vice versa
           }
   }).finally(function() {
       $scope.example7 += " (Finally called)";
   });

}]);

NODE

 app.get('/api/todos', function(req, res) {

    connection.query('SELECT p1.pat_id, p1.pat_name, p1.pat_birthdate,p1.pat_sex, p1.updated_time, t1.study_desc, t1.mods_in_study, t1.study_iuid, t2.series_iuid , t3.sop_iuid FROM patient p1 INNER JOIN study t1 on p1.pk =  t1.patient_fk INNER JOIN series t2 on t1.pk = t2.study_fk INNER JOIN instance t3 on t2.pk = t3.series_fk GROUP BY p1.pat_id;',function(err, data){
      if(err)
      {
        res.send(err);
      }
      res.json(data);

    });

I'm sorry for my English

via M. Node