SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e5b1ee6b9e61c0bd5a02dde4dd8a809317f2d6ef979808f52cbf437620c0886' 
  AND token = 'DXZRVfCBnOyWoEW5hey6IszufXmuWZYJHHvNCYDJO+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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