SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e0ea681309e40b1d142b25505611ff707c331d596b07b4c39e489b672ff9b49' 
  AND token = 'pRtwyznZyqbRFejsZNqsBykwi4/2V3znvrWaL5LwWKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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