SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c7a2c30b98b588de7c343d318fb5ab5264a8dd7912a8c4276a7b546ce1cdbe2' 
  AND token = 'g/wYp//Xl6+rZDE4fjb65QjlIiJGUcC9uO4GvDmZuhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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