SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdf380bd1e0457f5ddbf2bd3054295cbc9242d706c96f36530706d2b4c3f978b' 
  AND token = 'uVsuJEfz4exqP5DTcaBQT02TxbcZOFyYeTMKpyDhyTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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