SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca379e00a23eb07d23132d96b0ae6550f657ddcce7b8fd63132743b51e84a140' 
  AND token = 'y7PuWjdDaOvmszRGTdDwmSoFiwTBKcTrdLAVmqqNqdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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