SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f521651a383f3cc8657b6af9ead862a6290a7c4b222d6a46314c79aba5a56d1' 
  AND token = 'Nk1eCWvNkGJ+E7KOh1vMKAf8V9oWEfonOMHmWZkB2EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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