SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '900c6c49820e4b069f316486b1b903e13a9984e989c413f0f8b98b88ccf6bd78' 
  AND token = '/c4rMw7KhIaYjapmsre6ywqmq5YIQCpI+JF+GBTGKj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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