SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad9508f804f8a0208d315f33e1d0b25ca27e7a4b4283c5f69da627eb5c71f1fe' 
  AND token = 'Ez+u6U6M9IYmhy4Awa7rUMhmuWz8SGPcQlwBryDeCLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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