SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b7ef4fcd09a6c24128e2ce055144f752c8a5f886a0685a170460e22a042b733' 
  AND token = 'ok1uGErYQoFuFbRPA1UBDJ1OCpkOwYFWT+H9lljY5mU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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