SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ef404f6f060dbda94afc4a53d260794c3926e19542374cc1fc8590171e5d8b3' 
  AND token = 'SmzoZECZu4LMkozWps5CQPd/8u+gccFtXdjCRKsNOmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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