SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e953ef2ad2647c91a59a8bd2ad55ad1245552e7b873131b6cf1429054a525407' 
  AND token = '71luuG2aJ0FjWPzVH6klbLzgR5IzqC3kRfY16tKAeBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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