SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c703428b2ffa3240d0edffd97828b9fc7d6653c19d34eb08f19ebc4e1a3ff7' 
  AND token = 'SzeDvWCgb3S7xDnrA7xLiFSkg0aadvzZAASMR+RIJ5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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