SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c7d878f1b05a25facd1132d497c0425ff7689b57395d306868fa7bc7b7800e2' 
  AND token = '/ZET+RnX/ABsmgQC8kjZir23xMnD4Pdw7VuFawgGqws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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