SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba10a871c1afa429c07db43b3903c8d842c3ec4173e9475ff916915226bcb476' 
  AND token = 'MV6faijueKlBFqd/EwDrbwskLQp8iCEkDS9jBQ3rxTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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