SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e80963d41025af1e9fa567532a4ee61f055848396c1ceb82949b36b712ac393' 
  AND token = 'c/XVPtW0nWSjilL5NRh+YMY/IVuQy5E/cNK+ohvqcOU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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