SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2399911ae1e574f2bd30cb0584ed3cc7edac6d149b924d8c393a0d431445b9c6' 
  AND token = 'kHBvkLmYo7FI20xsdczgKB8UMjwzp3VBDYgSFl6PnZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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