SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b2492d7ddf0d6ec63978808db0704afb557e446a8dc4396c99c8082b74c075a' 
  AND token = '1NZWhF8yLzXJfhcvHbLYm7uUsxM30sBPVQTlTnsVfXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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