SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91b785706656e1e706207691911fececab03a69362bb6a11ada3d1b11123b98d' 
  AND token = 'Liu1E43sgTbJLSDB3Upq/dXSQGhkW8IZ7IfjFkziP6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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