SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46ba24e7ef7f86718eed581199216f050d521bfd71e68c3973989c084bb0a5c3' 
  AND token = 'mkQGx3ZfA8gex6cXMpmByqBv+IgvvoRcyhoJU9Zkuis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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