How to wait for an async to finish - NodeJs

I am using an async to do a second database query. The result of that query, must be added as an object to the first query.

The problem is that when the async is finished, the data hasn't changed, because he already sends the unchanged data. Is there a way to wait for the async to finish?

I have used a timeout, but the size of the data is unknown, so that isn't a good solution.

The code so far:

connection.query('SELECT * FROM SENSORS', function(err,rows) {
   if(rows.length !== 0) {
    DEBUG_WRITE('sensor/','GET',200);
    async.eachSeries(rows, function(row, callback) {
     connection.query('SELECT * FROM LOCATIONS WHERE LocationID=?',row.LocationID, function (error, result) {
        row.location = result; 
            callback(null,rows);
        });
    });
    res.status(200);
    res.send(rows);
   } else {
       DEBUG_WRITE('sensor','GET',404);
       res.status(404);
       res.send({status: "No entries found"});
   }
});

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