SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85694cf613f9e4ba5d3cd504e8bd89bf3d0cb6f19dc7968740b4a13be2ae1c71' 
  AND token = 'LA+QWDGXWdXMloEOMkzVIKbxdOiWfQ+s9P34DTJbetw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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