CREATE TABLE table_45 ("Scheme" TEXT, "Tariff code" TEXT, "BTs retail price  ( regulated ) " TEXT, "Approx premium" TEXT, "Prefixes" TEXT)

What prefixes are priced at pence per minute, fixed at all times with a premium of 3p/min?
SELECT "Prefixes" FROM table_45 WHERE "Scheme" = 'Pence per minute, fixed at all times' AND "Approx premium" = '3p/min'
SELECT "Prefixes" FROM "table_45" WHERE "Approx premium" = '3p/min' AND "Scheme" = 'Pence per minute, fixed at all times'