SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19c2211860ac5822a068547ec0360a45538c5143ff1657d51b91ead0a40199e4' 
  AND token = 'DC+QrDxwizO1iBBXS0vkYOyIOQhGIV9JDmrWMSygAKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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