SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a341845d4b6ee61c3d2e7c9c031fbe53336ea95b15ac33a67869d0a0d80be55' 
  AND token = 'UUujUulmN450rbnSiJbKY0q8hRlL3yhcFcKhiknZunU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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