Convert mysql datetime to timestamp to create a timeseries chart


I am new to Grafana and facing problem with datetime conversion to timestamp (MySQL). I am trying to create a timeseries chart.

I looked into similar topics for answers but failed to achieve the required result.
One of the solutions i tried:
UNIX_TIMESTAMP(date_insert) as time_sec,
temperature as value,
‘temperature’ as metric
FROM meteo
WHERE $__timeFilter(date_insert)
ORDER BY date_insert ASC