SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b81a97e1f11b9a954d37a6202c994d98f5654463d0c62b58458fe6a6cb78a6b9' 
  AND token = 'wDCqKqIArKT2+NQBtZgzRFi7NgRJoTz61OcH61SpB6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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