SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d517383eea972526f45acec0d8034635e60c51168434c251aaba8ab26fecee' 
  AND token = 'lbCCOsohKZ0W7TFhg4/7VjJ/cmTt+J3/+kEiRrC/eKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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