SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3405247939000cf45d684420843313c61f0a0958c40bddeae3b43ccf5957399' 
  AND token = 'PSoCRUs6DA6JGg7jl4nnf7YPhtVCeEgegg3COZKR6Hk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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