SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '671aa5906b0cf7548e76664f7e7b5eb788e0a7425d55e8fd201e8354dc7e7391' 
  AND token = 'PxUcbMyEWg0m9i/ahsAhjBt9BqjoNp3sJP+PZ/VkvTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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