SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '704125e4cba784f6249211db41c44b2d011a5911623b7e233f176b75fb8ce90d' 
  AND token = 'wC/Rzza0W8f88/zCQBo9MCbJ5LmZxKYUcek7/jmJPKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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