SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d03818669dec238af37623c5438366e9e3487556670b169f1d58a3be3b203d' 
  AND token = 'f95RohkkpJFfkngy/DfSvXuyZ4j9sVuNOHj/3oroYbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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