SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f43938707e1bd7644f99cfbb80315d11da6ec99d5f7480ee62d8e14c0df05d42' 
  AND token = 'dgpG/2FstkRw1IitPr7SV+d/K5IeBMWfUIzcSNXK2KY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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