SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fc4231c972dfe1c267c0ce84a689989304dcfa704e24e11dd73a442a87dd5cf' 
  AND token = 'xTeu1mXQgoIcscAnaQ/Xkp2xGAn4upfJLdfuP8/aFZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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