SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f8c34c56b195055f6f3c0e9fbcb54d786698a054a9d107318727c53fa940502' 
  AND token = 'UgG/ubqeyc9Zzt2+eXqAOFEx4lezGK7jjyElUWjHIo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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