SQLite Forum

This is a bit better I think:
    WITH cte AS (
        SELECT DATE('now', 'localtime')        AS now
        ,      IFNULL(MAX(lastUsedIdx), 0) + 1 AS idx
        FROM   selectRandom
        WHERE  lastUsed == now
    )
    UPDATE selectRandom
    SET    lastUsed    = (SELECT now FROM cte)
    ,      lastUsedIdx = (SELECT idx FROM cte)
    WHERE  description = :teaToBrew