SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf4f2d62a60013adad667558bac8edef8d9da3656718c904aa865cf366285b21' 
  AND token = '76WvUguolASlB8mQ8tdBKKxaA7ntQKlpC/nPyh9/+40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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