SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3fa1fd4626c7f198b94207728543f73bf96d733518c7af0a764fe5bfc75e2e89' 
  AND token = 'kdnswhin31XsY6YPsyg5MemVyrqwdlSKc/7hgd1aoe4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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