SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8212eaf21bfa87d118033bbfeaba838f26f319863b8a5c2621e350c29464af41' 
  AND token = 'fRm8+UdOffgEwv4eAp7LzwuEmjhIqrivSPuMJGyNb3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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