SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96bb8c528af720c70a39292de80bbc561c26970eb29ac55d02fdaff8265f17c2' 
  AND token = 'HUWR1TdkuPgDWuRy/ckplVsWb+A7wXZ9GZwEBl+gqAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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