SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9a3c708f7a1509d25dc555613c3f9e0552cf32eac7c60aee7fdf068be6db1c5' 
  AND token = '4LRGsSQ5FF9IOrFLHYfhMELzt1nKYhfEot00waapmFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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