SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '435d2f8c5e4868ed0dae919fe4eb90f4c5dd4d5bfd5ed419f35914edd0a21cef' 
  AND token = 'U0f/jMeUYCoUgx3mFeyyAh6CiLW2RxEjd6sypW9kA4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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