SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d9ca0521f275df1ef50bf3b37ecdfbfa1c578d1af38993162548fd9c2637e7c' 
  AND token = '3ytLM4lktQXClbqv48+4z7wgPk6ilhY2eElkd9HXUDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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