SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd75ac351efeb299e2290f47547815906cfb8c73d4525b374f228ce79809c1fd7' 
  AND token = 'HducVF19uihZzivIcocC6fgn68xVLqy4FOdb0WLf5VE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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