SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10a42058f93bfd5444e991a13f1e8dbd85b95df0f5020f0f23794ed6799186fa' 
  AND token = 'l/d/ZqjwDSyxuQzYsOeLs6wmxsPskwniEaEq24BbHQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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