SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c503cbaddcd100eeacbe2be50e5d69aadc01fea96347c8196ce42b8bf2e412a' 
  AND token = 'HWwg2z5TYWRd3Fq5znCbBEKBjCQK9j1o27jJcyMvfc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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