SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '669ee0049e154939a6d8be7a8a4fb4ba50848bee4604925ea312c7cbff054c36' 
  AND token = '9ZvKvWiTbnSVfDVCrW75LVe6ieg0qDsC/iE5+eUJgQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}