SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ca34ba81310f7f8518df3a724644bc1674070283174fa4637768d9d91317b03' 
  AND token = 'XPShqilIfCB8wnpdpARIEKjQ5irnILskh5vo5/j78gU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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