SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d8ed17a8c1d9f321a76bb2f5056d3199a82fec6a05e2e3ad7a64add62529426' 
  AND token = 'beQg4UEOWrzfLku0RbLJMO/RTxNjfGQXJfInwtXhxyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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