SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f99f59bb97f771b0323c75e49de7dd552d1882087d6539ee3ccfe18bb8d2ad2a' 
  AND token = 'sqxgtBsINXQIc8uwCD9weOcHcD0MjrSlwVpIEZakWJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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