SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e167284872d492add52f40cf63f2791ac1bbf6244baa5b955613c8e257f98f4' 
  AND token = 'LQzt9yqIPp1hxEjaJLk3A9DcMGsLZ5Mldn85W0V+hgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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