SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0847a4e6ce61bb420d975570ef34f2eb6ed021926f57095b6ad1b35d521809b9' 
  AND token = '15k7KkqrvDTKS4DfDCzXeHhW9XnoiTfUQe4MAsXMzCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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