SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '881388616a3f02379007ab3d6520c6a1c6967b9acfeb66a4d3360b7455c2a476' 
  AND token = 'vsB9Fh1olD6Hwmrt8yzeO7SJpj8rwIkPjJquFu0gqhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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