SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '115a0e58698542197559fb274343d4fc92cc96714671885017462e91692672cd' 
  AND token = 'uqRH9huWxw+jfKGxFCsaz5JZtsT+mxQfqpCFtMjxJrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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