SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6acd1f32729fc445a0a22632b2c93aa498aee0297a1753237013e291c07af1a1' 
  AND token = '8ZxPSWXj7UNmtkKEX34ciQiazcsiFeG0hlxAbh4UbCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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