SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '91175cf5283f797c94312081f279c333716296fa52b3ed0741b7e888b115665e' 
  AND token = '/TmdcGzf4D9UHfq9Zw+b3jtpyZANCZ0lddm5i26N2Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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