SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4cf52559e3e6cb538f34eefbf02aeac7b8f65cf92c27ff9ec6dc66cac635f41' 
  AND token = 'XEng5VytbANG3FSnKQPrYJoRJ3YHK/0lotdDj3qETYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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