SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fd5ea19dea3da9c7aeb66b73f81f9504c36b5354d2d73412cfa64f81a13b4e5' 
  AND token = 'NDj5xyhC8TdT6EUlvEwjF4qIfFDBmlq+U1LFV2K/vHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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