SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0015403df4ca4d974ef69e48f372e449ab865311ff0358b2dbc2f9a9862a2615' 
  AND token = 'leCb47apj4NJor7GPfVxPanf4E/N7WJebRtNIq02HSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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