SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcd979f26023252b7552667be72180889e4ca462552cb14875e4074ddd4ae421' 
  AND token = 'dZLwTOg5mrdyKCKV//BvZzT94iDukkTVpU+vxDmdtW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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