SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759e9b85e5d20c3084abce22689049682117bd5f1871c4bd5504b510759c5f51' 
  AND token = 'egFAmRfs+F5XEcGabAK1GJQzz5xmgzy0+xJev4+dsyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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