SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ffc0011a61a4cf56f7da879591a1d4eae4cf30212d55f7826b79569748e1e2cd' 
  AND token = 'vKz3Z5RSusiupR+61NloZ81aaqvO0jxuS9lZYcUQKwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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