SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9a83bb8ebdec6d9653b219a2fd655c92eae0bb9e9656290285b21eb132ee3a2' 
  AND token = 'keoSUJz4TiopenjSt27fWi4WLBUzcD5yBZMzxzpVt+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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