SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21940175a458854839413271f845ad41ffd06dcc61332f607c7b47afb5f8b13a' 
  AND token = '4y1NtlnFYgrpUx/tAkdoM3zSoZB2xqEBzwE6Y748Cew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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