SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8de4df525ac6960a69f15db196af3df6ebd1484fb3854657b3df66e1ae772f68' 
  AND token = '34uZNihV63JIWtvAUywZQDrI1pDN0D2sK22fUQKwGsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}