SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3128429cb990ff74c7c2f357582ac08bb2fad4f0be8fd285a60908661a31e2b0' 
  AND token = 'xBAwU3WWIAxmyFP+ez2BUpeBMrh7+IAg/1GaU6VKEyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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