SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3416184dc24a1efc832a942fd95987cde53d822dbbdeb1b9840b0e74496cc14' 
  AND token = 'DvffYnvkNDOWl7lkoeh9rnXbb6EYrbS4t1M/jSddOaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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