SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6adc8ba105241304204a04f5aea52689f518439b92b802acbf1c6e2e6769030f' 
  AND token = '7saFp2xNTvnl7rEUtLmqnqi6rqc6hIjY96DD9jlNgW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}