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()
);
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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;
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