SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f40c3c1d79934a91fdecf094c24b6c0f4ff703fca585f8e7b4511990673aedfd' 
  AND token = '/BmvrR0tC8ZVGwPDjZVVUHwpdYLaGtdIbHLg5jZjNB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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