SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f66363ae00e43a6cfee81b25742236c19cb46000904deafd5104f0314ece2016' 
  AND token = 'U/FLuIUKE1z2YzQpoXvKADw1+oTlQAIdECfvHBZnVjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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