SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd15b344928a6047158d92c4baf703786def02d5f6739e804fa8c7778453ba8d' 
  AND token = 'wblAmjRi6BolmMtL1pBzCDS6zdD+XwvxTMAubaPpob4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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