Data in hours/seconds interval is not displayed


i am using grafana to display electricity data power/time
my data source is mySQL Database
the data is in a table which contains 9 million dataset
i am using this Query for selecting data in Grafana :

datetimestamp AS “time”,
FROM werte
ORDER BY datetimestamp

MyProblem :

By selecting Data between days, the data comes and displayed in the panel

When i try to make the interval smaller between hours or seconds the data doesn’t come and nothing is displayed in the panel

Can you maybe try to clear for me why is this issue happenning in my panel