SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a13d5afa47fe4d230f0729fc472b80db664f1439857716076af5174b0858738' 
  AND token = 'ptHlAjp6+XdIzWR6lVtRhy3uoLnWKbopWqvXAUk2PHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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