SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8287536a58d3a1982577e61f71ce67baacfaba7289d158d0a881108fc012a60' 
  AND token = 'gku5/ARnYQbmvOPrXJWwHaghWp5s45mykHTMQQcePR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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