SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12633692e736926acc0379902dfed8855b6781221f0c312484d1b78513a7fb73' 
  AND token = 'nU0eVoEJY8GxSHKaaJwNQqKzey5MudpD4TJIQkea3dI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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