SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '351694361046ab73353bbfe8e7cca81ad9c1d43e1e9c0c4754c67aea287c7d79' 
  AND token = 'fQiTUf1s9O37zDRSe+4d/FY5/gk31qa+0BCol7ITC+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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