SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b468969cf877a159739bfa6fa85315b1da04439b49b8253f4be0d9405e6329c1' 
  AND token = 'dRVw8DLMc48Gofzyl9hzr+UOjTXlcvHVL0j2wN8AqXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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