SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd6947766dfb99fee9d6b74f333f58589994e381b04f2b64d410a8812a37cbac0' 
  AND token = 'sx7h+wcB9kyHN5IatWjN0KPtx7MzoRClxggEcyDdzQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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