SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f7dc445ca3f09fbb1736eea1e4ddb407fccd2da0c6a790d4db64ce12b3b7cbd' 
  AND token = 'YFrHtQ9cwGtv80Di+AthBabbF/hoTZT2n5f0BvA2o+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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