SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398d6725a7cd420c93d2f893180201fba4d8be913cca1c43ab993b375000d8f8' 
  AND token = 'LgXkQpq6Umw1Nq48zn6dSIep8VINeUQwFj4iTDlgnlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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