MySQL select where variable is not in row
===

I'm trying to do MySQL query to extract specific rows without the help of PHP if conditions,

okay,<br>
i want to select a row where the variable is not in a specific row but here's the thing

    $blocked_user = "aaron";

and in MySQL

    +----------+-----------------------+
    | id       | blocked               |
    +----------+-----------------------+
    | 1        | aaron,john            |

i want it to skip "aaron" while selecting and process to john
<br>
a false example :

    SELECT * FROM table WHERE $blocked_user NOT IN blocked

What i was doing is get blocked content and seperate them using php explode function then using in_array and if to confirm its not there :

    if(in_array($blocked_user, explode($row['blocked'])){
      exit;
    }

but now i want to get rid of this and do it using a single query, how is it done ?