SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e833846ee27136b442d9da2b824f2bc38277f23d8409f3a36417b18ecd16e961' 
  AND token = '0U+NZ+V8VF70sRv9GTYRzM/p3SYlJERFS7Y8bhTJOj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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