SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9eafb94d881996a76e1aadba5e26978240f25c1dd13a7392bb4987b35f9dc037' 
  AND token = 'xTKgNsLOMXQIztd5hrICbtdDEnP1pmvcDyipiamleS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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