Query data at specific timestamp

Hi everyone,

I would like to query data at a specific timestamp from a database where a datapoint for this timestamp not necessarily exists.

Example:
I would like to query data at “2020-04-02 02:30:00” from the following measurement table:

time                    value
==================================
2020-04-02 01:00:00       10
2020-04-02 02:00:00       20
2020-04-02 03:00:00       30
2020-04-02 04:00:00       40

Since there is no data available for this timestamp I would like to get data which got somehow interpolated, like the mean between the two closest datapoints or even just the closest or the previous datapoint.

I saw that one can do interpolation in a group by statement (https://www.influxdata.com/blog/working-with-irregular-time-series/). So my question is if there is a way to get interpolated data at a specific timestamp in a single select-statement as well.

best regards,
Marvin