SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87528e31d32845ee286840b8eb5cde308a9ed5c62559a7e4f4f03c577d1822eb' 
  AND token = 'ZJWWJk5I+iKcJ/izVQ4M4L7+tgj6aGblSYV0ZDCcUjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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