SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18ed8cb23b3d4f761a032bc19d08572cd1698e0b36e0aa88f296a6bf55136c47' 
  AND token = '/jkRjzQNDBX3JL2sKgs79uEQZHru2P00XCnotiql5Ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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