SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50d6f0caa80286b0c3ae38b069577ab9ab59bca6780ea41724b69acfb8548da2' 
  AND token = 'nLO+RgPSjzpTqoYL+11nvZu1H3ScB6W7vBMNV8hUn8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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