SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70c6948b793b15d699b8ac2e290fa3cd08e6a804367af59bb277c7a47820b5d0' 
  AND token = '6YiOXnxP76EuVrgbjDwbGbGA3wXVcsnXJ70+iELM3Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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