SELECT 
    @diff:=ABS( UNIX_TIMESTAMP("2021-09-31 08:00:00") - UNIX_TIMESTAMP() ) , 
    CAST(@days := IF(@diff/86400 >= 1, FLOOR(@diff / 86400 ),0) AS SIGNED) AS days, 
    CAST(@hours := IF(@diff/3600 >= 1, FLOOR((@diff:=@diff-@days*86400) / 3600),0) AS SIGNED) AS hours, 
    CAST(@minutes := IF(@diff/60 >= 1, FLOOR((@diff:=@diff-@hours*3600) / 60),0) AS SIGNED) AS minutes, 
    CAST(@diff-@minutes*60 AS SIGNED) AS seconds;