SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56840c5b1baa39aa39a816872aa0a72f95f747b7dd4ac38d8771c2ee9c0d0f83' 
  AND token = '43IZyMxu+kZQgSwg6UK/f6fkigQVMaIpW8mP63SPBzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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