SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0bae831cb2e30b50fb181bb89402300b4a828af46eaf46676092da1419768711' 
  AND token = 'g10TElLeJbPy1LFbtBDpKM36oTj/iT3RU6+oZBkGYtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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