SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f1a5143a0160192bedd7c305de3f7dc96fcd7ddbfe62d281595888b67546c3' 
  AND token = 'jv8ykflXSkj49Sjl+SJeQCveZbAQ4Js1Ju9zxtuAxKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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