SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12337adf4022d4220dec93e16abe4653b076ad83df1c925621b9f07141945986' 
  AND token = 'u5K/WgiSPY2V/VtMCZnauQmBCG461cLrJchJ9DXhFjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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