SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c12ddd4a68951b2d5c63b9db0f2d2e74bb495b68dd04a58aeb96d6d00fc84605' 
  AND token = '57s6C/sUfIvPCfXzpxvY7KEjDdMm+87zettpEWjknfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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