SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c645fbeaa46dd2a8bcd8fe12ecb152df1b097025283aaf7daee570ce4096ce46' 
  AND token = '5S7Mwg/Wed1NMTGEGOjvi9+uzr68lKvyydElu9jPbDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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