SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be9fc9da17e86b90738ff1cd45da916d815508bc457043fa2af9a335467bc5e9' 
  AND token = 'egnWEuH6SyPswWbxPc5yGqx2aBGT9NdO8sJCNFqHneY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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