SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ce2257f5ba4fb1772b5430b09efef5ba9fbdb1ceffd50177996a1f69fb32cc3' 
  AND token = 'L/r+aIUIqA0p4qYWBMBltJm+7KtRnWwWcqjbnavwxzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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