SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92fc922893faac08af9f0c7730189fa8028a6ff69b60c79983a73ba9abf8e12' 
  AND token = '5tWqxRvfzYQxr/oAfa70XR+XVujWuwAxBoZdruF//sM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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