SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d1e747d23409035119b295d5a919bb8fb5df950babc8ea7d04acabe38ee877' 
  AND token = 'sYdNgNXTgWpR4wRAY+tJpgnQDPtDOKKHxM4oX30iaNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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