SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '515e1720aa767e8af4100caa76241f4c3b2395e7b68b8e1dffcf6b9bcf14ef01' 
  AND token = 'YF9YBla/WeGgS06BmVxKm48JjOhD7gfqxCNjqFDi+7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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