SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c644f4de8c87f6816b605253488b76bc372b01db25573be315eb1f706de4456b' 
  AND token = '7UOhcDWhBpkkPv4LGrjOVNa6schkt1nNUHjySB2F/JA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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