SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dc76068dc48161d15a17b099a187aaf47fd869c6818c02e07685a53d4b48c00' 
  AND token = 'QutKWoiYkGiZMKzHHgb0Cv6NASnxxfkSk+iMsOWqUVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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