SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fff17ac72a97d87543b471f864cabba143111a9656611c067285de7105d3834' 
  AND token = 'oxyajgt6sy1NeKPu7P6Bx02rRwPmflQSH+baR4fCXRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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