SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a87b8be208b556282a532edc558042e070a6bb8344b717c7f59af084f87f411' 
  AND token = 'OSJe2oX8r2TtoKdtdSnxoLVWwxIKBaOdLWUkv+pwzQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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