SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473f2f856f212a129ac955ec2c97523519e552e4a7d3696c46b4c217b48b3a0b' 
  AND token = 'AJcKlhsnjZ+zUUc4BhxWmR3PpyZIVHPNLy4NjTvXvJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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