SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3978eb69ded2cc56523fef5b02c6cac03dd3e95f9bf414a3f3fbfd02e17f72c2' 
  AND token = '3fy99GR3GPCgQdypmz1ylnTBYSXQVvFtYl5H7bVmSTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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