SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c73f9e05849642694c3f69a512936e17ae85c9e1f5cdf9a26eb3e014e0922af' 
  AND token = 'llk4xDgj88tKAO7P9BoLDzzbXMwgWsQvSAlfAQixc6E=' 
  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"
    }
  }
}