SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a118e6b16e76c1979a324da11f94a7922ba2d74475ea8f713db618742102d36f' 
  AND token = 'b+KVOTOeiedgkLFSOwZgFpa6qDQOD9bRt0qpsced+mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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