SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e977a52282c5cabc913c3e78123a5a3bc280660446a48a6e2597da2a2672b2af' 
  AND token = 'fPQSpDaGCLcyokrCrGf9olHeoVS9lTiw2bB//Zcd598=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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