SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79ecb69550f189c42075abf97ebc170f421705b2f6682997057179b541e98795' 
  AND token = 'BS53cJE1NwbccTFNWfxmEm2fTieWpE103aM96YkpGJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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