SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec1b58ece3b369e09737d29ecd250036e80208e5107f804dcee087a869b1a271' 
  AND token = '0KvdFVvQ9yiz5BgDAQpbGB0mNByvvBQce1PFARNd/Ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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