SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2589860239aafefbf98b7a9b3beec7c960c5f510015f8d84008322fcad64a640' 
  AND token = 'PzGrZNO4w0oHZBEBPJ1XcRoKvLlehcHL/GWNNejuzQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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