SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d2e6b22eb25a4455f338e89a5feda54446fc36e76cfc7fc00feb7af66bc8a76' 
  AND token = 'Kb8jZtKvB45DZrHsnh3BLd8rrCtQohhFMyIJP+bZJKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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