SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e40b36d0bf8f97eecc0cda9188fe844d7d78684aa20018172070b643ff15a731' 
  AND token = '9+ZJaogodnF2acpEMrO4MN0+C/mqzvtYAJ+KUHAWQ40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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