SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f71927c0649baed8c6a36418899be2e1c1c7a51268837bb554a770a064158e8' 
  AND token = '8jqFQWCmeGnR4TKDFU0E+mGFjXdPtXv+/EhiyzgHMq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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