SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909b4fb581d610a3ac265bf0cb52e7d05d36fc183ab09545fb4a1a1c4cf4db66' 
  AND token = 'Ku4wVgGFiQjyyFZh3WcO8HG1+zN6wO9CrUWV4rv2V1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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