SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16d175340e38014997c04627ba8ef0c2911e4745256e9255ca8eee36465340b5' 
  AND token = 'T2OxvHgQAFf5CD0WdgDuKvdlXTuN09O+lcGvFWtSm5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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