SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9306d21bb2549a346dcd4ddce444af6a6ebc12090f1e731b73e0cc1f9741e6ba' 
  AND token = '3lVPm7MULwnBbixsbcDBJxAlEaAwZg63E0PXgSCIC6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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