SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a458c5543de636f88fe08de2bb2f2d32662dfd66961b54f346b408fa55913e8' 
  AND token = 'V0KzLgqt8ArWxnwBdCSVJrKCSQ5SsTy2QpJOmZkxJRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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