SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a99985fc91b72bc40d5fada64805eb42bbffaed6fe4dd4a62df6a914518f960d' 
  AND token = 'pFNgvdQlQi2RiZ5LRp4pJFEIxPA5krPeumWt+do4TIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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