SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3993a109471b4dbc95ccfef099e7cd30e3cdc87a50e26e5dc30e121bd2f6936e' 
  AND token = '0i9jMts1cFcabfVmRJp+fgCluyRZV3jE8FJ5op8US58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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