SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3688cab764bd6749d8cae13cda834c868b81b2470bb0db6047c8731a7e2a293' 
  AND token = 'zDSllXjjdNCupQIWtQf7HQ03+J19lZiUAFe+qaOhyoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00068

JSON explain

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