SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0455c72bd1d9fc3fec25d24dfb52c61b39e2a4a28207018db78616dc1ffd4d47' 
  AND token = 'so1tZg5sPpVxDRzZBuGgbQwhsYLlC+mQRd6tjeyjee0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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