SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d76c2f4dcb6ef910d8898a1208067a897450dd712e308973047a3c6203d9999' 
  AND token = 'E8ldmmYicBM2ByQMHS+DPyeYPEbZLNRFzK83Ynz3Jh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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