SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a8b2e4303e24192074294a704638a4d059a7a53b302ca51875a2171247fc27b' 
  AND token = 'O7hiaOHJVdkJpj9Zq5I+TdZNsAS0P2XQFW8v2+s/HFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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