SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d06a36c363703249c2d577ffcc6bf56a5ccb825550da446077a424aa284bb28' 
  AND token = 'n33xwH9h+XtvHjGil+swg0mzoJOlPkTfbnUAijgB2HQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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