SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3208cfe5fd84858faea980f1638c45a4dd45cca471936016c71cb1defd0f427d' 
  AND token = 'QbAC6mHR1tnckjKXJqsBRbwDGrFsv+rAjmqQGAHJESI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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