SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b36f611fb0a52a35a91c85308757657a71738d2b47bdf48ed00643d57929d7da' 
  AND token = '2juqrfVHrzZxK+eHF5CoFsHpoXXw6SWb04MB2hBLGgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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