SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a450699f37f10bfd002b210e551ae9cee4d42efb7eabf4db42d2c0d974d1c171' 
  AND token = 'AKZ3vdcOHGPk5poeUGrL0oNE51EuJqLq4VaRCt4bITM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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