SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6209fd4155b9d12c265733d5861c6c5f6f806daa8f5febe054fc39064bfa1b7' 
  AND token = 'YQ92b2DdV+w0NhiPfRern6JsJsWlzvRk9HZZnPQlt80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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