SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15832d7f3c95bfa5e9106bd46da43faafc6b2eb0823fe91eba271fb5ca1c945b' 
  AND token = 'jUJZQvBBqzwifbgST7K6/zD3Sr13ajeV2CrwHSAp0Mw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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