SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '540df80c7ef0b3213a998a73103d6a6ef4675bb66c7d5ca966774f26e70039de' 
  AND token = 'COXmA4BoGD6CQhLa2mYjvKixlVEgfZM/IhXZviRUcmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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