SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831112d2eafc016e7286e8b5f56482b73dd23da55e0060d0aa60a459e59b7201' 
  AND token = 'Fj9oJO4v86CEBIBnKjFm/vCRaEB5uGZriGslSMBVYVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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