SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7849b6ba1962b9fe32dd834fac817378626776d50b2ce97dcc951d154206c9c' 
  AND token = 'v9r9gE/ah1E7RrtaCwKj/W5z1+gsxox2vxDhY6qCqmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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