SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1599ddd9340a8e2467fd23d5fbeaf0c84393d24ee66dd21ca49a5e0cf933c73f' 
  AND token = 'eh+lr8pyHAET7TdOyJ4znkh14Qe/jpxgBliCODoNW0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}