SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e8fd15a89c550e773565383851a44b4404bafd31ce3cf2b2a09752f2f04a136' 
  AND token = '4xUKa7jdS9GZ+uf/HROhf47kRznamOtO0YwqO5ABjrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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