As
haukex points out, you can use the database functions to calculate the difference. You can select the interval between now and the timestamp you have like this:
SELECT TIMESTAMPDIFF(
MINUTE,
STR_TO_DATE('Tue Oct 23, 2018 - 19:57:12','%a %b %d, %Y - %T'),
NOW()
);
That will return the difference in minutes - you can use SECOND as well. In your SQL query you might have something like this:
SELECT
column_name,
TIMESTAMPDIFF(
SECOND,
STR_TO_DATE(column_name,'%a %b %d, %Y - %T'),
NOW()
)
FROM table;