SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8bfc185652b4ebbdcd4b7bca3f2abfe21b64b72339ab233313baed0ff3ab7b6' 
  AND token = 'SOTHR1gTIUwFxKKLv/liInkwH8Sob1uI+9xU14PPkJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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