SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd794db36d49e517944f87ba89c0063eb7447618ecae1f976f0a816509ae758b4' 
  AND token = 'O42xDRzzrZLYG1UPvktJUIJ0ttI0AyzYApOJmApkbAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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