SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b13ed37b65f401b6ad2e502bb504eb70bda37658acfa8ade060e53b099eae978' 
  AND token = 'g10XLkvcaziWt2IEY12xIfFe9pk3opRJKqBKV7RupcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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