SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855bf6f15dcc8350890d4ff3ccd923c84051a2460b1272d6c6c96ad96073db70' 
  AND token = 'Syycwq+AGv3L6CQSzHMlcPtuGtVTI1Zi3ZDPC+Jd5zo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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