SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'beaa4b80065818aea45622a7327937bd2d760dfb5c2c2dc64b48d6c368adc72d' 
  AND token = 'DkzsnkkCPscZovIOcXgUfcLt7lEx8poO1dV4x44Nre4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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