SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c292999bec2f037e2cbe4e50175a67546d3fa039b7e3eec1003f603d31788df7' 
  AND token = 'N/JLM4frrjvV0z4e30RBGJKuZvXHskhKE/xSGbjSYBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}