SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54a1b6dd8f68b16770b2559375e199584344572ebab44609ae2bdedd31e8e9b6' 
  AND token = 'tfP3wPvwsAwjrdr/SHunYvq+R9HoTIfTaVx16fbvxL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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