SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f8c35adf6f4fb09d40275bccddcad045977c6572793f30eec26758aa18fe04f' 
  AND token = 'zQx7tUopABL4FLV7NWjXPDRZNYc21jTmxgMVCFqi+2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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