SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '388ac54886975d9c585098dcaf0541ec3c9dd21e11ba314e5a527a247be8cf79' 
  AND token = 'P5RzwYKsnPkCb8eThG18uoO6LEBvWyHKdKImofK7KDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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