SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71313122d96933afb1ccc369933ebde383f7cdc0662ad55106f8227621aff544' 
  AND token = 'Kf/6Z0wKCFqNDGICYlFhomNrTIhH3zZzfNE0sJgp5iI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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