SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7542b681f45881cd3c2a636a733bb5c98395f62dab465b5f7706aa86dafe1af8' 
  AND token = 'I//1zLujolZ83EeK3zhC8/svtJ4zJ+GJWTUzGZ9nEwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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