SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b461a051e557d91a9633072e96bb91b0c39a4b7f111660423a3d74a32b3037a3' 
  AND token = '+RPaiyrJChmkKPyhr98Wj5xlf1QfchnlXcPH5nSJQjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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