SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ea7688d4a99dfcc5ac5a4225a9c9eaf27a27c1218930b259e9aeda21e5e014b' 
  AND token = '4+VUiS4+8HrMrTVBZkkPQHtzUFvmNHn4xRGtSX1J65Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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