What is the average lap time for retired time of +23.707 and a Grid greater than 21?
CREATE TABLE "125cc_classification" (
  "rider" text,
  "manufacturer" text,
  "laps" real,
  "time_retired" text,
  "grid" real
);
SELECT AVG("laps") FROM "125cc_classification" WHERE "time_retired"='+23.707' AND "grid">21;