SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dabcba89ee0c30fde0d7a575264ba743e7c519b740d8815ca458ac91d40e5f8' 
  AND token = 'apccHSf57Xa8dcTXSOFNpaUMdkQL9JCL+hpMutJRelQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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