SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b7cd9bd522a3c454198979e9fbd747e9f80874025fdf1d5e1ac63267b9b4734' 
  AND token = 'MAeqeQm5HXsjpN8swBWfLw8BXjJy9uKqoqfnilurZaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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