SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7560eb451b1b4251d567fbb09bb504f0d62bf42f91e069c4cc1edf68131b3815' 
  AND token = '78BSVxiIZvvvgr61K/UKpZN9qbRcTY8CzNlSd/gZlJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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