SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fe6e81ee04f494059d2081fffb90c4f376a93a356b19acb829a6248a3033571' 
  AND token = '1lBzp+47DL9e/3YdLO9MJl506FiN4qZZO5FrzrghDAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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