SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '517fa572004cba8101bc19d0631b1e9bd34008d836f468108754f25feadfd1ef' 
  AND token = '5GFJp/iUFsUprmOxTRziorKdng5AXNrJaHj8fJuw2GE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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