SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98b9fda53dc85766905746349a294625ef8766722c8dae0b2ceef5042f6b2f1' 
  AND token = 'hsfr9vZNmxotHLT4ZV4eAd5LJPoFvKhWM8U4gDurivA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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