SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27359795fb023395e8caa4a52da966d88a1cb46c26625120b5480747a5109f57' 
  AND token = '5Bl1CaIjFOsrEEKVAZaklEVmMGTpIUp4qc8EF4Bf0GU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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