The /services/databases/system/SYS_CACHES table contains details of the cache refreshes.  Run a query on this table, and look at the values of the INITIAL_TIME and LAST_REFRESH_END columns.

Example
Get the last refresh start time, end time and duration for a cached resource named "v_Refr".
The full pathname of the cached resource is shared/TESTS/cac_refr/v_Refr.

Query
    select 
          INITIAL_TIME,  LAST_REFRESH_END, STORAGE_USED, LAST_SUCCESS_DURATION
     from
          /services/databases/system/SYS_CACHES 
    where 
          RESOURCE_NAME like 'v_Refr%'

Result
    INITIAL_TIME                           :    2018-02-23 13:22:49
    LAST_REFRESH_END            :    [NULL]
    STORAGE_USED                    :    0
    LAST_SUCCESS_DURATION :   0