SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7cc646652acc3c4b384285e8c76630ae049ca1fe58f354deacdfd9ea1b4b736' 
  AND token = 'rkDkaoVoC6u4OvU0ARWmWwIzobdZwVRbthfI+aGGpW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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