SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b8ef50baa67862df09f912d8408e16676b721a6246bd9820cbf5c80c6deac24' 
  AND token = 'vZqSfhxBdIlwne7GaF5O87tbpmaZBjVqS6CNFCWXgJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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