SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21052702c13ba9a63f46cc2a8fb6503379fb6ff6c161d15211d8b471d46af262' 
  AND token = 'd1f0EUn0PqfqZgjAVTOUjQ4dpEyhMB0etqfTBMK8YO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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