SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51dbfb413615aa109182dd49a4f88d31b1acf6da725fceddeb375c0df8d07661' 
  AND token = 'Sks/2vzd9QGs4GEeNbG1iKW7lF05RcnIFsS4ipfzQWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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