SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a24560b80ecea86c8640a25343cfbba6c59ce155c8f05dbf9d2d8849380154d' 
  AND token = '16CkUUjZqFZzAywMm54zfM7Fa46XvevtWzw2Bdah5zY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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