SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '521424bda839c7657b1e21fd5271e62184ec24bfbcd6fa512f2661fc223df3c9' 
  AND token = '+DjNCOeXRS6JdBw+lEEuRckbmyTzYBGYt2HwJMi/2JM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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