SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '016dc70cde390f2681f59cfbb956fabd410b9b1bbcbfbb675fc63d66574d6b71' 
  AND token = '8xRUp+PogKYDbqanH1k9AVVP3CzoKTycYc0BcgJZ+sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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