CREATE TABLE table_name_56 (laps INT, grid VARCHAR, time_retired VARCHAR)

What is the mean number of laps when the grid is less than 19 and time/retired is +21.3 secs?
SELECT AVG(laps) FROM table_name_56 WHERE grid < 19 AND time_retired = "+21.3 secs"
SELECT AVG("laps") FROM "table_name_56" WHERE "+21.3 secs" = "time_retired" AND "grid" < 19