SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b0af9a5b4612542054431849ad6ab9f39826fb6c64e72f0472d1b1b6adfe5b2' 
  AND token = 'Iq9TIfUY4MCKf7UYLMLdeDDYmlEdUyUMwVsgcLyC8t4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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