SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7322f31d534fc759a170a035d7d78b4915df6d8aeae3106b4219f51304853ccb' 
  AND token = '3Do2IkziTxlhnitp71VOZJURX0+r6h5lvV3oFBsVAxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}