SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87f5fd841bba0ca78889198892200add10e0cedaafd5a9fe32277dbc34f70699' 
  AND token = 'FMjruh7LmMUyZbfEx9gWhvy+DYV9sfUsWVh3tcCSHsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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