SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '975bdf996f3963410c74c58cafee4b9caa01bd5e95fd48985e2ba4376e6a66e1' 
  AND token = 'dRURSsLo43tUYAaxkrrzlXdcyeL8ayzAjJDp7kJa7yg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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