SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17a4c2718360f241b36176fd23c8663abe6771437db8c94f6174da4855843cf7' 
  AND token = 'UgFZNbQm2ak38OhL7OkUz1tLhlB9dW6dGxNbxci3zc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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