SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '691643fb8bc8bd4cd12a16ddfc560ec36b549e17d789b7aba14dae046e44c494' 
  AND token = '7zzQPBXXKa8n1FKFK5vCcOeRWqomA2GhS+MuuaRdWlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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