SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3249895e378cfa1e3138d82fb3d4e36082cf490b27c19a3e46cf25dee4c4b2' 
  AND token = 'hUD6KuLTjCLV+gYLgdTL+mPCYGq7ilmfw9W8/wMt/g4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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