SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57f1df61c5162c19850b77d343dbd5988be50593226a4582359ecec51191b647' 
  AND token = 'RVkeC5RlVkkX3UsopF5jYFPlQL5rzHp08Ku53feItFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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