SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38b55a775192788dc918b7a18d2c8c492ffab869094137e9dfbafabb563b8e3c' 
  AND token = 'DJOBgpwsDjJxksZXurOVqAynsBekh1VvCHIDt9AZMfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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