SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f34fb72749b14f7ddf0442e3fca685649e3deae4c709e46c36353dcf41938371' 
  AND token = 'VXUn6Zo+GmY0yBJScEz9xNgMP7mOiTT0z7wGxK/erJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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