SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5473168911ae6cd38962640af6a3f572cbc4b991eed1ffced365ca16df771aae' 
  AND token = 'pTy+rcZBWK/6uQj9rAKXzsTH9TdHSWZMhYsArIkAo2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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