SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8e6dfc1538b5017b299742e8cb695d5647cf6558ea014d71ac1edd80aa70342' 
  AND token = 'WStEzE3njCucT1I8WhYD7h753KV0j+wHmabqU3ROhLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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