SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'bbd2f02132cdc06edafc76c46f6b5c6448603390b2acb96dff0783708e130832' 
  AND token = 'Z81+jLZBNxGHvxAfBn971Bq+JsUTusrY/nhEKj7QcjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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