SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b4813dc98f4b8a93f014eed181e743203cdaf03d36bfd82420bf20632d23536' 
  AND token = 'P+11MASyv/XKoPBAmMnRujRpf3zfK+syrgTJcx418yQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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