SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '856bef558225971c51d28217a7375b9c86f64ffc02cd3d3e1c974120159b9627' 
  AND token = 'OLZ8/MKZ+LUFNRFJKl9tCVmCSpq43aLWt/m5cjBd4Lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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