SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b38663d0a3edc6f9c6001f0967414d21c50295abaa4c2a75adf60b52dffbc27' 
  AND token = 'XiscZeWw+5G3+xvQ02jFhs14uDO1IBjdXQ1PzBnZiys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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