Business As Usual in OKR parlance is often a synonym to KPIs or metrics which would be measured in the normal way with or without OKRs. For example - "Visitors to Website is 1 million" is a BAU metric.

An example of Key Result would be - Objective: Improve effectiveness of social campaigns in holiday season in order to drive sales

KR 1: Increase organic social referrals to website from 0.5 million to 1 million

KR 2: Increase social referrals to on sale product from 100k to 150k

KR 3: Increase referral revenues from social referral coupons from 10 million to 25 million