SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823a81d2efe810fb07721163afd7efd2404114e5fff572719c79dd27f0dbcae9' 
  AND token = 'UdQZWfOKIfKqjPJh+og7mFOVXY2mRfuoSJ2JlGcVQDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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