SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd138fc41b6537241d5739930afe80d0d001b760cf5b7851028e36b09a680144' 
  AND token = 'PEpZyaB6VvK7HzY/yTVrwD7YDlFWSK2iQnubujSHsoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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