SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a7e5ac89bf7baf27dc76c9357f7a05ff9fb1e9aa1437121b3492203c50ee227' 
  AND token = 'wj6pgZWqnZBZnVh+67fi/ROR/7YC1AKRobXwlrTi7Ac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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