Blockchains are increasingly attractive due to their decentralization, yet inherent limitations of high latency, in the order of minutes, and attacks on consensus cap their practicality. We introduce Blinkchain, a Byzantine consensus protocol that relies on sharding and locality-preserving techniques from distributed systems to provide a bound on consensus latency, proportional to the network delay between the buyer and the seller nodes. Blinkchain selects a random pool of validators, some of which are legitimate with high probability, even when an attacker focuses its forces to crowd out legitimate validators in a small vicinity.