SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12f8d8e6366e043cdfd876cd087726755947fc3057c693dbbdbbad064de761d2' 
  AND token = 'nG3MhXiiteV2fUTuNwJbZHRe7fT+IewBctWKGaSLMwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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