SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ac93788caf0afe7fc18dcace338896f4ab1c4393efa291d4cf659bedc7ec9ec' 
  AND token = 'xub/12v2Goaeeho7GuQc45bwB0qH1oImiYmlVzyIvt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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