SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b157fdd0641781e377781efa9739ef55751abc5d9c44f1ec63bb80686afbc423' 
  AND token = '9CsEUJzN70kGgqKcwwWbXH2jmjFE91fCvHnsqNA8RgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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