SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ca0174df7464af350031ede712306e7e9f697dbd32effa5582679900d68288' 
  AND token = 'Y2HDVTs+utDQl4fz7zzvaHyXveQRhjOd9Lscl2zrdVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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