SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '483a68547845426b1b3b39a947f307e971a3f4e051d9c6215de852e5da49dc96' 
  AND token = '/kJE8NIXmhVs1mCv9haWcJqpBElAXeGUMUzqhQ+CfPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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