SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b79634e070336f955865472f6bdc04b3c1b2620087af19e15f88d2887985f764' 
  AND token = 'aEsCQQNEL6NlkZaxib+vo/NPqZzlQ0uoe30jOShwh1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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