SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c583ad46e20d7299dccf743c2c151c581572c74e6f789d81678ed685e7401cf' 
  AND token = 'AOKrcK95N2O05GbFxCYPhxIElqFBfI+sSNPq2OwKkDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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