SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76929f7c1ee3e3659cfa128f60ff39bab058350f8bb562acc6be7c48e71b639b' 
  AND token = 'Jj5LdGbFAznYycCdmlvHTOWOpwncVwijGcvXHOvD+4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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