SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '677fe8fabd1269918e9144148b53949791c52eb98db4bdecf1ca066b134caa63' 
  AND token = 'x6CMSRWuDwQzgNZJataS3fSncxDsvWS8+c3wQBjmkNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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