SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a2fba9e12dcfa62847382c1e9fcd641fa13254dee87cba4237239aa8412b602' 
  AND token = 'k7pKIN3PgGtv7wwwP/KvSGSAC3AhNfXNKaTATHCmMpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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