SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cffea0c1cfe94b0e6eff74cc0c4d2884615be01bb9825c42a3d0e8413aa0a9ab' 
  AND token = 'ssBfDKuKqMCDZb9eZcS9OkJiXgwE0GDYlk0bW7not0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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