SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6968a1c52bdc7f138f0d9e411a72fc9aff3cbc8a860530ae534562976c195f45' 
  AND token = 'z/Q5CKC/8SOakPFIpErlBjxpGSmgeKMrZGWaac/i+UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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