SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd28d60a71872b52a89f59f7d51d8edd6d5d8ed3d332419723963aafafda6304' 
  AND token = 'JaiZNYrNXgzr2CYgo2uc/Ug40jJcZUIYxx/R52SuXls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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