SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e35857c991bda30a125bd7536b260312a6932b67543fada2a8b97c8f45906e61' 
  AND token = 'i5mrlpMcQ/01k9ceck3/IfwN+Za/6VXX4IvR6p9pdgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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