SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9944980655e29b2502555dab3a8b86366d90264ab0a4280cfbb44d4053e2bf' 
  AND token = 'JUtJpmBj5gdhbWKAUEytBRXBsP+ONYKhCTvXAp0M5LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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