SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42edda52345b62c46bf959317bca7097c1e541d32597fc6fbabe9cdafc023f70' 
  AND token = 'fbbj4TwZ3mz+Um3J0HksBNYbB8kOB81Jxp8NlAVLSNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}