SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b3ca42af1b1913b0654840d1b422dcebf29f6a99733eeeb264c9b47a47769d4' 
  AND token = 'MplWLkHaGhlUU3YCpsKmv+bPoUp0BkwySUDKnJs6Gw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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