SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d9c3e59fa848ea01f539685cf69d23b0662d42f69779f7d2633d170a8a966f2' 
  AND token = 'UP8iAvWeBqxP6/vHoXjyfm9zBlbOW3qFy1UdgcNDKSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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