SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2137bef75a827a0ff2c7e6234660047e3b7803fc5d3e1cd31fd8f8d9e7517de7' 
  AND token = 'A7MBZSICbFy1wNzQM7qSXmqfcCJXkFCrdo6BrWykaZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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