SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0904a3fb03bc719e2a35accebf74d0d7256efee74ae273f117a7a4638edf03cd' 
  AND token = 'KfHUiw7RFMlVxrZaf8tYQarLmkZWEiHN+dPlZd6Re4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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