SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '816702830bf66d98758e22c2994f90b6389e5ee13cb974435ec52849206e73d0' 
  AND token = 'FysJEyA4xPVvK++ImJh/N1RJNLEzbpwjOTDn6uVq6tA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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