SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c35d974270bcf7d3a4394a86803bb7acea50a753e6bee93a9658fd5377e7e4f6' 
  AND token = 'gjYXYYKKc+amo4jPYekpfkYTjGVL8/9w6dTZm7zcuC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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