SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec4ebcdca03285bd9a5651d45cb5e39912f3e7fb60e1abae4f607360f466ae28' 
  AND token = 'dveDgKyVxWcPNhpDuKV70rNhuHq13/BFBzZoqEHGOAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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