SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c53e5e17389dd155078744b65974a6d7f5432a1ce48bbc784adad4407a43f21f' 
  AND token = 'uCYRRyuzkFKDByi3tnkQV1vq9Ltdy54fpq+HwnW6hV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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