SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e66b48bc7971f175645f26d421a954644565dfac53e8bfd6a5da913b88dd2f5' 
  AND token = '73q/ZYoEG7nSF1kfq4mfC/FI1ZvE8jSVGCjrVHFtRVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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