SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f3dcdac59f5af0d753ab17389cc87291e4c5204046f9b8f909cf76820469c29' 
  AND token = 'iZEGnAjwpsvKDYv3lR049+01dsYzVk+LdsXLOTtrvXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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