SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '997788b52e4f9d18fe255f86c6dc23a3bbb8fa1c138b66a4245fbd79537b1e73' 
  AND token = 'FOnVRhEggrZdhOAemJuN1dRvbdIM6qLRewBTL1Hb2B8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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