SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b182f56e97fff32adc09397b99f6ee66a685aa46224a979de8de7d5b70a5b0' 
  AND token = 'cq+RPwU1Lqf0kABYt3vvGl45hBKagyjyxUAiTRV23cs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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