SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40e81914839f75eb3c13d5dead3cbde7f2a9a8a950db444210b2e76e83fff584' 
  AND token = 'xzfGvE3MSscLhGPla5zgfPjCy60SnJ232PQY97RfqOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}