SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a46f1a524ad33dc3cd53ddb815c28b9c5c3b9af1939490173c19655c32ed267' 
  AND token = 'ART/LmvTqmSD7O8QnCbS4aBBXQU+TCODihnUnK7KuYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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