SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c69afc3533f4f9e8a3b039ee29aee0c9c8ebc4392071172e3398097b6051cb81' 
  AND token = '+iHx2V2UEKxzCjY1zSgjsoTv7/VcdWnlMgQr8hmYUtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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