SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b21e2a0ffd1251eb4dd2be3bf1342b49dfeab99a642b553c53132016b63a99c' 
  AND token = 'iHLApCLLUqBbWwTcoQ/k1zjddm7ZLNyeyJo9+7hDnNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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