SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75a2282bc60632cb61553860d11417b0bec651ff8291297c768bf2feffa57a9b' 
  AND token = 'JACv4WYSA1Di4eOmoXNrgQVUFVuMHBskHsgh4Tqeo/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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