SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd0282e19373f104b91d01dc56843b356c9a890fa4fcb4b9a71470358635c345' 
  AND token = '9Q84p7RCe+xJUjkWW75ws1mwr2NWiwOZL5YgKMsubz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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