SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fe94063ddb6b9ecff8a0a9ac8bfc2f62ae93e94141898366dbad4f12b85b1d2' 
  AND token = 'P+xofiJ3YH8FKhd55krtq+DSIAS+FzJZvxXWg/zQohg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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