SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '865006726d31d1899fa8822426931e0e2ac8b8259cd804e2bdce744629a09631' 
  AND token = 'Kz5vl6ewjOGmduFGVIHxgwIulPG+DJmg3L3bYfE4aHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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