SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e514c8d6cc58729112ffdf3d3c338611b160408475e39fbf27dae7aa63d44bb6' 
  AND token = 'Kg4zsmLPCM5ikp8dqxhOYSt1+nLvQmKJzIzuIlKsMwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}